[v3] Late service registration and error handling overhaul (#4066)

* Add service registration method

* Fix error handling and formatting in messageprocessor

* Add configurable error handling

* Improve error strings

* Fix service shutdown on macOS

* Add post shutdown hook

* Better fatal errors

* Add startup/shutdown sequence tests

* Improve debug messages

* Update JS runtime

* Update docs

* Update changelog

* Fix log message in clipboard message processor

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* Remove panic in RegisterService

* Fix linux tests (hopefully)

* Fix error formatting everywhere

* Fix typo in windows webview

* Tidy example mods

* Set application name in tests

* Fix ubuntu test workflow

* Cleanup template test pipeline

* Fix dev build detection on Go 1.24

* Update template go.mod/sum to Go 1.24

* Remove redundant caching in template tests

* Final format string cleanup

* Fix wails3 tool references

* Fix legacy log calls

* Remove formatJS and simplify format strings

* Fix indirect import

---------

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

.github/workflows/build-and-test-v3.yml

@@ -30,7 +30,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [windows-latest, macos-latest, ubuntu-latest]
-        go-version: [1.23]
+        go-version: [1.24]
 
     steps:
       - name: Checkout code
@@ -40,7 +40,7 @@ jobs:
         uses: awalsh128/cache-apt-pkgs-action@latest
         if: matrix.os == 'ubuntu-latest'
         with:
-          packages: libgtk-3-dev libwebkit2gtk-4.1-dev build-essential pkg-config
+          packages: libgtk-3-dev libwebkit2gtk-4.1-dev build-essential pkg-config xvfb x11-xserver-utils at-spi2-core xdg-desktop-portal-gtk
           version: 1.0
 
       - name: Setup Go
@@ -66,11 +66,25 @@ jobs:
         working-directory: ./v3
         run: go test -v ./...
 
-      - name: Run tests (!mac)
+      - name: Run tests (windows)
-        if: matrix.os != 'macos-latest'
+        if: matrix.os == 'windows-latest'
         working-directory: ./v3
         run: go test -v ./...
 
+      - name: Run tests (ubuntu)
+        if: matrix.os == 'ubuntu-latest'
+        working-directory: ./v3
+        run: >
+          xvfb-run --auto-servernum
+          sh -c '
+          dbus-update-activation-environment --systemd --all &&
+          go test -v ./...
+          '
+
+      - name: Typecheck binding generator output
+        working-directory: ./v3
+        run: task generator:test:check
+
   test_js:
     name: Run JS Tests
     needs: check_approval
@@ -105,41 +119,23 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
         template:
-          [
+          - svelte
-            svelte,
+          - svelte-ts
-            svelte-ts,
+          - vue
-            vue,
+          - vue-ts
-            vue-ts,
+          - react
-            react,
+          - react-ts
-            react-ts,
+          - preact
-            preact,
+          - preact-ts
-            preact-ts,
+          - lit
-            lit,
+          - lit-ts
-            lit-ts,
+          - vanilla
-            vanilla,
+          - vanilla-ts
-            vanilla-ts,
+        go-version: [1.24]
-          ]
-        go-version: [1.23]
     steps:
       - name: Checkout
         uses: actions/checkout@v4
 
-      - name: Setup Go
-        uses: actions/setup-go@v5
-        with:
-          go-version: ${{ matrix.go-version }}
-          cache-dependency-path: "v3/go.sum"
-
-      - name: Setup Golang caches
-        uses: actions/cache@v4
-        with:
-          path: |
-            ~/.cache/go-build
-            ~/go/pkg/mod
-          key: ${{ runner.os }}-golang-${{ hashFiles('**/go.sum') }}
-          restore-keys: |
-            ${{ runner.os }}-golang-
-
       - name: Install linux dependencies
         uses: awalsh128/cache-apt-pkgs-action@latest
         if: matrix.os == 'ubuntu-latest'
@@ -147,15 +143,26 @@ jobs:
           packages: libgtk-3-dev libwebkit2gtk-4.1-dev build-essential pkg-config
           version: 1.0
 
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: ${{ matrix.go-version }}
+          cache-dependency-path: "v3/go.sum"
+
+      - name: Install Task
+        uses: arduino/setup-task@v2
+        with:
+          version: 3.x
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+
       - name: Build Wails3 CLI
+        working-directory: ./v3
         run: |
-          cd ./v3/cmd/wails3
+          task install
-          go install
+          wails3 doctor
-          wails3 -help
 
       - name: Generate template '${{ matrix.template }}'
         run: |
-          go install github.com/go-task/task/v3/cmd/task@latest 
           mkdir -p ./test-${{ matrix.template }}
           cd ./test-${{ matrix.template }}
           wails3 init -n ${{ matrix.template }} -t ${{ matrix.template }}

docs/src/content/docs/changelog.mdx

@@ -54,6 +54,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add `//wails:internal` directive on services and models to allow for types that are exported in Go but not in JS/TS by [@fbbdev](https://github.com/fbbdev) in [#4045](https://github.com/wailsapp/wails/pull/4045)
 - Add binding generator support for constants of alias type to allow for weakly typed enums by [@fbbdev](https://github.com/fbbdev) in [#4045](https://github.com/wailsapp/wails/pull/4045)
 - Add support for macOS 15 "Sequoia" to `OSInfo.Branding` for improved OS version detection in [#4065](https://github.com/wailsapp/wails/pull/4065)
+- Add `PostShutdown` hook for running custom code after the shutdown process completes by [@fbbdev](https://github.com/fbbdev) in [#4066](https://github.com/wailsapp/wails/pull/4066)
+- Add `FatalError` struct to support detection of fatal errors in custom error handlers by [@fbbdev](https://github.com/fbbdev) in [#4066](https://github.com/wailsapp/wails/pull/4066)
+- Standardise and document service startup and shutdown order by [@fbbdev](https://github.com/fbbdev) in [#4066](https://github.com/wailsapp/wails/pull/4066)
+- Add test harness for application startup/shutdown sequence and service startup/shutdown tests by [@fbbdev](https://github.com/fbbdev) in [#4066](https://github.com/wailsapp/wails/pull/4066)
+- Add `RegisterService` method for registering services after the application has been created by [@fbbdev](https://github.com/fbbdev) in [#4066](https://github.com/wailsapp/wails/pull/4066)
+- Add `MarshalError` field in application and service options for custom error handling in binding calls by [@fbbdev](https://github.com/fbbdev) in [#4066](https://github.com/wailsapp/wails/pull/4066)
 
 ### Fixed
 
@@ -81,6 +87,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Suppressed warnings for services that define lifecycle or http methods but no other bound methods by [@fbbdev](https://github.com/fbbdev) in [#4045](https://github.com/wailsapp/wails/pull/4045)
 - Fixed non-React templates failing to display Hello World footer when using light system colour scheme by [@marcus-crane](https://github.com/marcus-crane) in [#4056](https://github.com/wailsapp/wails/pull/4056)
 - Fixed hidden menu items on macOS by [@leaanthony](https://github.com/leaanthony)
+- Fixed handling and formatting of errors in message processors by [@fbbdev](https://github.com/fbbdev) in [#4066](https://github.com/wailsapp/wails/pull/4066)
+-  Fixed skipped service shutdown when quitting application by [@fbbdev](https://github.com/fbbdev) in [#4066](https://github.com/wailsapp/wails/pull/4066)
 
 ### Changed
 
@@ -98,6 +106,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Update copyright date to 2025 by [@IanVS](https://github.com/IanVS) in [#4037](https://github.com/wailsapp/wails/pull/4037)
 - Add docs for event.Sender by [@IanVS](https://github.com/IanVS) in [#4075](https://github.com/wailsapp/wails/pull/4075)
 - Go 1.24 support by [@leaanthony](https://github.com/leaanthony)
+- `ServiceStartup` hooks are now invoked when `App.Run` is called, not in `application.New` by [@fbbdev](https://github.com/fbbdev) in [#4066](https://github.com/wailsapp/wails/pull/4066)
+- `ServiceStartup` errors are now returned from `App.Run` instead of terminating the process by [@fbbdev](https://github.com/fbbdev) in [#4066](https://github.com/wailsapp/wails/pull/4066)
+- Binding and dialog calls from JS now reject with error objects instead of strings by [@fbbdev](https://github.com/fbbdev) in [#4066](https://github.com/wailsapp/wails/pull/4066)
 
 ## v3.0.0-alpha.9 - 2025-01-13
 

docs/src/content/docs/learn/bindings.mdx

@@ -448,3 +448,149 @@ const promise = MyService.LongRunningTask("input");
 // This will cause the context to be cancelled in the Go method
 promise.cancel();
 ```
+
+### Handling errors
+
+As you may have noticed above, bound methods can return errors, which are handled specially.
+When a result field has type `error`, it is omitted by default from the values returned to JS.
+When such a field is _non-nil_, the promise rejects with a `RuntimeError` exception
+that wraps the Go error message:
+
+```go
+func (*MyService) FailingMethod(name string) error {
+    return fmt.Errorf("Welcome to an imperfect world, %s", name)
+}
+```
+
+```js
+import { MyService } from './bindings/changeme';
+
+try {
+    await MyService.FailingMethod("CLU")
+} catch (err) {
+    if (err.name === 'RuntimeError') {
+        console.log(err.message); // Prints 'Welcome to an imperfect world, CLU'
+    }
+}
+```
+
+The exception will be an instance of the `Call.RuntimeError` class from the wails runtime,
+hence you can also test its type like this:
+
+```js
+import { Call } from '@wailsio/runtime';
+
+try {
+    // ...
+} catch (err) {
+    if (err instanceof Call.RuntimeError) {
+        // ...
+    }
+}
+```
+
+If the Go error value supports JSON marshaling, the exception's `cause` property
+will hold the marshaled version of the error:
+
+```go
+type ImperfectWorldError struct {
+    Name string `json:"name"`
+}
+
+func (err *ImperfectWorldError) Error() {
+    return fmt.Sprintf("Welcome to an imperfect world, %s", err.Name)
+}
+
+func (*MyService) FailingMethod(name string) error {
+    return &ImperfectWorldError{
+        Name: name,
+    }
+}
+```
+
+```js
+import { MyService } from './bindings/changeme';
+
+try {
+    await MyService.FailingMethod("CLU")
+} catch (err) {
+    if (err.name === 'RuntimeError') {
+        console.log(err.cause.name); // Prints 'CLU'
+    }
+}
+```
+
+Generally, many Go error values will only have limited or no support for marshaling to JSON.
+If you so wish, you can customise the value provided as cause
+by specifying either a global or per-service error marshaling function:
+
+```go
+app := application.New(application.Options{
+    MarshalError: func(err error) []byte {
+        // ...
+    },
+    Services: []application.Service{
+        application.NewServiceWithOptions(&MyService{}, application.ServiceOptions{
+            MarshalError: func(err error) []byte {
+                // ...
+            },
+        }),
+    },
+})
+```
+
+Per-service functions override the global function,
+which in turn overrides the default behaviour of using `json.Marshal`.
+If a marshaling function returns `nil`, it falls back to the outer function:
+per-service functions fall back to the global function,
+which in turn falls back to the default behaviour.
+
+:::tip
+If you wish to omit the `cause` property on the resulting exception,
+let the marshaling function return a falsy JSON value like `[]byte("null")`.
+:::
+
+Here's an example marshaling function that unwraps path errors and reports the file path:
+
+```go
+app := application.New(application.Options{
+    MarshalError: func(err error) []byte {
+        var perr *fs.PathError
+        if !errors.As(err, &perr) {
+            // Not a path error, fall back to default handling.
+            return nil
+        }
+
+        // Marshal path string
+        path, err := json.Marshal(&perr.Path)
+        if err != nil {
+            // String marshaling failed, fall back to default handling.
+            return nil
+        }
+
+        return []byte(fmt.Sprintf(`{"path":%s}`, path))
+    },
+})
+```
+
+:::note
+Error marshaling functions are not allowed to fail.
+If they are not able to process a given error and return valid JSON,
+they should return `nil` and fall back to a more generic handler.
+If no strategy succeeds, the exception will not have a `cause` property.
+:::
+
+Binding call promises may also reject with a `TypeError`
+when the method has been passed the wrong number of arguments,
+when the conversion of arguments from JSON to their Go types fails,
+or when the conversion of results to JSON fails.
+These problems will usually be caught early by the type system.
+If your code typechecks but you still get type errors,
+it might be that some of your Go types are not supported by the `encoding/json` package:
+look for warnings from the binding generator to catch these.
+
+:::caution
+If you see a `ReferenceError` complaining about unknown methods,
+it could mean that your JS bindings have gotten out of sync with Go code
+and must be regenerated.
+:::

docs/src/content/docs/learn/services.mdx

@@ -40,9 +40,9 @@ greeting.
 ## Registering a Service
 
 To register a service with the application, you need to provide an instance of
-the service to the `Services` field of the `application.Options` struct (All
+the service to the `Services` field of the `application.Options` struct.
-services need to be wrapped by an `application.NewService` call. Here's an
+All services need to be wrapped by an `application.NewService` call.
-example:
+Here's an example:
 
 ```go
 app := application.New(application.Options{
@@ -70,6 +70,25 @@ ServiceOptions has the following fields:
 	- Name - Specify a custom name for the Service
     - Route - A route to bind the Service to the frontend (more on this below)
 
+After the application has been created but not yet started,
+you can register more services using the `RegisterService` method.
+This is useful when you need to feed a service some value
+that is only available after the application has been created.
+For example, let's wire application's logger into your own service:
+
+```go
+app := application.New(application.Options{})
+
+app.RegisterService(application.NewService(NewMyService(app.Logger)))
+
+// ...
+
+err := app.Run()
+```
+
+Services may only be registered before running the application:
+`RegisterService` will panic if called after the `Run` method.
+
 ## Optional Methods
 
 Services can implement optional methods to hook into the application lifecycle.
@@ -98,8 +117,12 @@ func (s *Service) ServiceStartup(ctx context.Context, options application.Servic
 
 This method is called when the application is starting up. You can use it to
 initialize resources, set up connections, or perform any necessary setup tasks.
-The context is the application context, and the `options` parameter provides
+The context is the application context that will be canceled upon shutdown,
-additional information about the service.
+and the `options` parameter provides additional information about the service.
+
+Services are initialised in the exact order of registration:
+first those listed in the `Services` field of the `application.Options` struct,
+then those added through the `RegisterService` method.
 
 ### ServiceShutdown
 
@@ -110,6 +133,9 @@ func (s *Service) ServiceShutdown() error
 This method is called when the application is shutting down. Use it to clean up
 resources, close connections, or perform any necessary cleanup tasks.
 
+Services are shut down in reverse registration order.
+The application context will be canceled before `ServiceShutdown` is called.
+
 ### ServeHTTP
 
 ```go

v3/examples/dev/go.mod

@@ -1,17 +1,17 @@
 module changeme
 
-go 1.23.4
+go 1.24.0
 
 require github.com/wailsapp/wails/v3 v3.0.0-alpha.0
 
 require (
 	github.com/Microsoft/go-winio v0.6.2 // indirect
 	github.com/bep/debounce v1.2.1 // indirect
-	github.com/ebitengine/purego v0.4.0-alpha.4 // indirect
+	github.com/ebitengine/purego v0.8.2 // indirect
 	github.com/emirpasic/gods v1.18.1 // indirect
 	github.com/go-git/gcfg v1.5.1-0.20230307220236-3a3c6141e376 // indirect
 	github.com/go-git/go-billy/v5 v5.6.2 // indirect
-	github.com/go-git/go-git/v5 v5.13.1 // indirect
+	github.com/go-git/go-git/v5 v5.13.2 // indirect
 	github.com/go-ole/go-ole v1.3.0 // indirect
 	github.com/godbus/dbus/v5 v5.1.0 // indirect
 	github.com/google/uuid v1.6.0 // indirect
@@ -22,26 +22,26 @@ require (
 	github.com/kevinburke/ssh_config v1.2.0 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
 	github.com/leaanthony/go-ansi-parser v1.6.1 // indirect
-	github.com/leaanthony/u v1.1.0 // indirect
+	github.com/leaanthony/u v1.1.1 // indirect
-	github.com/lmittmann/tint v1.0.4 // indirect
+	github.com/lmittmann/tint v1.0.7 // indirect
-	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-colorable v0.1.14 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mitchellh/go-homedir v1.1.0 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421 // indirect
 	github.com/modern-go/reflect2 v1.0.2 // indirect
-	github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8 // indirect
+	github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/rogpeppe/go-internal v1.12.0 // indirect
-	github.com/samber/lo v1.38.1 // indirect
+	github.com/samber/lo v1.49.1 // indirect
 	github.com/sergi/go-diff v1.3.2-0.20230802210424-5b0b94c5c0d3 // indirect
 	github.com/stretchr/testify v1.10.0 // indirect
 	github.com/wailsapp/go-webview2 v1.0.19 // indirect
 	github.com/wailsapp/mimetype v1.4.1 // indirect
 	github.com/xanzy/ssh-agent v0.3.3 // indirect
-	golang.org/x/crypto v0.32.0 // indirect
+	golang.org/x/crypto v0.33.0 // indirect
-	golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56 // indirect
+	golang.org/x/exp v0.0.0-20250210185358-939b2ce775ac // indirect
-	golang.org/x/net v0.34.0 // indirect
+	golang.org/x/net v0.35.0 // indirect
-	golang.org/x/sys v0.29.0 // indirect
+	golang.org/x/sys v0.30.0 // indirect
 	gopkg.in/warnings.v0 v0.1.2 // indirect
 )
 

v3/examples/dev/go.sum

@@ -18,6 +18,7 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/ebitengine/purego v0.4.0-alpha.4 h1:Y7yIV06Yo5M2BAdD7EVPhfp6LZ0tEcQo5770OhYUVes=
 github.com/ebitengine/purego v0.4.0-alpha.4/go.mod h1:ah1In8AOtksoNK6yk5z1HTJeUkC1Ez4Wk2idgGslMwQ=
+github.com/ebitengine/purego v0.8.2/go.mod h1:iIjxzd6CiRiOG0UyXP+V1+jWqUXVjPKLAI0mRfJZTmQ=
 github.com/emirpasic/gods v1.12.0 h1:QAUIPSaCu4G+POclxeqb3F+WPpdKqFGlw36+yOzGlrg=
 github.com/emirpasic/gods v1.12.0/go.mod h1:YfzfFFoVP/catgzJb4IKIqXjX78Ha8FMSDh3ymbK86o=
 github.com/emirpasic/gods v1.18.1/go.mod h1:8tpGGwCnJ5H4r6BWwaV6OrWmMoPhUl5jm/FMNAnJvWQ=
@@ -39,6 +40,7 @@ github.com/go-git/go-git/v5 v5.3.0 h1:8WKMtJR2j8RntEXR/uvTKagfEt4GYlwQ7mntE4+0GW
 github.com/go-git/go-git/v5 v5.3.0/go.mod h1:xdX4bWJ48aOrdhnl2XqHYstHbbp6+LFS4r4X+lNVprw=
 github.com/go-git/go-git/v5 v5.11.0/go.mod h1:6GFcX2P3NM7FPBfpePbpLd21XxsgdAt+lKqXmCUiUCY=
 github.com/go-git/go-git/v5 v5.13.1/go.mod h1:qryJB4cSBoq3FRoBRf5A77joojuBcmPJ0qu3XXXVixc=
+github.com/go-git/go-git/v5 v5.13.2/go.mod h1:hWdW5P4YZRjmpGHwRH2v3zkWcNl6HeXaXQEMGb3NJ9A=
 github.com/go-ole/go-ole v1.2.6 h1:/Fpf6oFPoeFik9ty7siob0G6Ke8QvQEuVcuChpwXzpY=
 github.com/go-ole/go-ole v1.2.6/go.mod h1:pprOEPIfldk/42T2oK7lQ4v4JSDwmV0As9GaiUsvbm0=
 github.com/go-ole/go-ole v1.3.0/go.mod h1:5LS6F96DhAwUc7C+1HLexzMXY1xGRSryjyPPKW6zv78=
@@ -76,14 +78,17 @@ github.com/leaanthony/go-ansi-parser v1.6.1 h1:xd8bzARK3dErqkPFtoF9F3/HgN8UQk0ed
 github.com/leaanthony/go-ansi-parser v1.6.1/go.mod h1:+vva/2y4alzVmmIEpk9QDhA7vLC5zKDTRwfZGOp3IWU=
 github.com/leaanthony/u v1.1.0 h1:2n0d2BwPVXSUq5yhe8lJPHdxevE2qK5G99PMStMZMaI=
 github.com/leaanthony/u v1.1.0/go.mod h1:9+o6hejoRljvZ3BzdYlVL0JYCwtnAsVuN9pVTQcaRfI=
+github.com/leaanthony/u v1.1.1/go.mod h1:9+o6hejoRljvZ3BzdYlVL0JYCwtnAsVuN9pVTQcaRfI=
 github.com/lmittmann/tint v1.0.0 h1:fzEj70K1L58uyoePQxKe+ezDZJ5pybiWGdA0JeFvvyw=
 github.com/lmittmann/tint v1.0.0/go.mod h1:HIS3gSy7qNwGCj+5oRjAutErFBl4BzdQP6cJZ0NfMwE=
 github.com/lmittmann/tint v1.0.3/go.mod h1:HIS3gSy7qNwGCj+5oRjAutErFBl4BzdQP6cJZ0NfMwE=
 github.com/lmittmann/tint v1.0.4/go.mod h1:HIS3gSy7qNwGCj+5oRjAutErFBl4BzdQP6cJZ0NfMwE=
+github.com/lmittmann/tint v1.0.7/go.mod h1:HIS3gSy7qNwGCj+5oRjAutErFBl4BzdQP6cJZ0NfMwE=
 github.com/matryer/is v1.4.0 h1:sosSmIWwkYITGrxZ25ULNDeKiMNzFSr4V/eqBQP0PeE=
 github.com/matryer/is v1.4.0/go.mod h1:8I/i5uYgLzgsgEloJE1U6xx5HkBQpAZvepWuujKwMRU=
 github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
 github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
+github.com/mattn/go-colorable v0.1.14/go.mod h1:6LmQG8QLFO4G5z1gPvYEzlUgJ2wF+stgPZH1UqBm1s8=
 github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
 github.com/mattn/go-isatty v0.0.19 h1:JITubQf0MOLdlGRuRq+jtsDlekdYPia9ZFsB8h/APPA=
 github.com/mattn/go-isatty v0.0.19/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
@@ -97,6 +102,7 @@ github.com/modern-go/reflect2 v1.0.2/go.mod h1:yWuevngMOJpCy52FWWMvUC8ws7m/LJsjY
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
 github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8 h1:KoWmjvw+nsYOo29YJK9vDA65RGE3NrOnUtO7a+RF9HU=
 github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8/go.mod h1:HKlIX3XHQyzLZPlr7++PzdhaXEj94dEiJgZDTsxEqUI=
+github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c/go.mod h1:7rwL4CYBLnjLxUqIJNnCWiEdr3bn6IUYi15bNlnbCCU=
 github.com/pkg/diff v0.0.0-20210226163009-20ebb0f2a09e/go.mod h1:pJLUxLENpZxwdsKMEsNbx1VGcRFpLqf3715MtcvvzbA=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
@@ -114,6 +120,7 @@ github.com/rogpeppe/go-internal v1.11.0/go.mod h1:ddIwULY96R17DhadqLgMfk9H9tvdUz
 github.com/rogpeppe/go-internal v1.12.0/go.mod h1:E+RYuTGaKKdloAfM02xzb0FW3Paa99yedzYV+kq4uf4=
 github.com/samber/lo v1.38.1 h1:j2XEAqXKb09Am4ebOg31SpvzUTTs6EN3VfgeLUhPdXM=
 github.com/samber/lo v1.38.1/go.mod h1:+m/ZKRl6ClXCE2Lgf3MsQlWfh4bn1bz6CXEOxnEXnEA=
+github.com/samber/lo v1.49.1/go.mod h1:dO6KHFzUKXgP8LDhU0oI8d2hekjXnGOu0DB8Jecxd6o=
 github.com/sergi/go-diff v1.1.0/go.mod h1:STckp+ISIX8hZLjrqAeVduY0gWCT9IjLuqbuNXdaHfM=
 github.com/sergi/go-diff v1.2.0 h1:XU+rvMAioB0UC3q1MFrIQy4Vo5/4VsRDQQXHsEya6xQ=
 github.com/sergi/go-diff v1.2.0/go.mod h1:STckp+ISIX8hZLjrqAeVduY0gWCT9IjLuqbuNXdaHfM=
@@ -145,9 +152,11 @@ golang.org/x/crypto v0.16.0/go.mod h1:gCAAfMLgwOJRpTjQ2zCCt2OcSfYMTeZVSRtQlPC7Nq
 golang.org/x/crypto v0.19.0/go.mod h1:Iy9bg/ha4yyC70EfRS8jz+B6ybOBKMaSxLj6P6oBDfU=
 golang.org/x/crypto v0.21.0/go.mod h1:0BP7YvVV9gBbVKyeTG0Gyn+gZm94bibOW5BjDEYAOMs=
 golang.org/x/crypto v0.32.0/go.mod h1:ZnnJkOaASj8g0AjIduWNlq2NRxL0PlBrbKVyZ6V/Ugc=
+golang.org/x/crypto v0.33.0/go.mod h1:bVdXmD7IV/4GdElGPozy6U7lWdRXA4qyRVGJV57uQ5M=
 golang.org/x/exp v0.0.0-20230626212559-97b1e661b5df h1:UA2aFVmmsIlefxMk29Dp2juaUSth8Pyn3Tq5Y5mJGME=
 golang.org/x/exp v0.0.0-20230626212559-97b1e661b5df/go.mod h1:FXUEEKJgO7OQYeo8N01OfiKP8RXMtf6e8aTskBGqWdc=
 golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56/go.mod h1:M4RDyNAINzryxdtnbRXRL/OHtkFuWGRjvuhBJpk2IlY=
+golang.org/x/exp v0.0.0-20250210185358-939b2ce775ac/go.mod h1:hH+7mtFmImwwcMvScyxUhjuVHR3HGaDPMn9rMSUUbxo=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20210326060303-6b1517762897/go.mod h1:uSPa2vr4CLtc/ILN5odXGNXS6mhrKVzTaCXzk9m6W3k=
 golang.org/x/net v0.0.0-20210505024714-0287a6fb4125/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
@@ -157,6 +166,7 @@ golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
 golang.org/x/net v0.19.0/go.mod h1:CfAk/cbD4CthTvqiEl8NpboMuiuOYsAr/7NOjZJtv1U=
 golang.org/x/net v0.21.0/go.mod h1:bIjVDfnllIU7BJ2DNgfnXvpSvtn8VRwhlsaeUTyUS44=
 golang.org/x/net v0.34.0/go.mod h1:di0qlW3YNM5oh6GqDGQr92MyTozJPmybPK4Ev/Gm31k=
+golang.org/x/net v0.35.0/go.mod h1:EglIi67kWsHKlRzzVMUD93VMSWGFOMSZgxFjparz1Qk=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190507160741-ecd444e8653b/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190916202348-b4ddaad3f8a3/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -180,6 +190,7 @@ golang.org/x/sys v0.15.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.29.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.13.0 h1:bb+I9cTfFazGW51MZqBVmZy7+JEJMouUHTUSKVQLBek=
 golang.org/x/term v0.13.0/go.mod h1:LTmsnFJwVN6bCy1rVCoS+qHT1HhALEFxKncY3WNNh4U=

v3/examples/file-association/go.mod

@@ -1,21 +1,21 @@
 module changeme
 
-go 1.23.4
+go 1.24.0
 
 require github.com/wailsapp/wails/v3 v3.0.0-alpha.7
 
 require (
 	dario.cat/mergo v1.0.1 // indirect
 	github.com/Microsoft/go-winio v0.6.2 // indirect
-	github.com/ProtonMail/go-crypto v1.1.4 // indirect
+	github.com/ProtonMail/go-crypto v1.1.5 // indirect
 	github.com/bep/debounce v1.2.1 // indirect
-	github.com/cloudflare/circl v1.5.0 // indirect
+	github.com/cloudflare/circl v1.6.0 // indirect
-	github.com/cyphar/filepath-securejoin v0.4.0 // indirect
+	github.com/cyphar/filepath-securejoin v0.4.1 // indirect
-	github.com/ebitengine/purego v0.4.0-alpha.4 // indirect
+	github.com/ebitengine/purego v0.8.2 // indirect
 	github.com/emirpasic/gods v1.18.1 // indirect
 	github.com/go-git/gcfg v1.5.1-0.20230307220236-3a3c6141e376 // indirect
 	github.com/go-git/go-billy/v5 v5.6.2 // indirect
-	github.com/go-git/go-git/v5 v5.13.1 // indirect
+	github.com/go-git/go-git/v5 v5.13.2 // indirect
 	github.com/go-ole/go-ole v1.3.0 // indirect
 	github.com/godbus/dbus/v5 v5.1.0 // indirect
 	github.com/golang/groupcache v0.0.0-20241129210726-2c02b8208cf8 // indirect
@@ -24,26 +24,26 @@ require (
 	github.com/jchv/go-winloader v0.0.0-20210711035445-715c2860da7e // indirect
 	github.com/kevinburke/ssh_config v1.2.0 // indirect
 	github.com/leaanthony/go-ansi-parser v1.6.1 // indirect
-	github.com/leaanthony/u v1.1.0 // indirect
+	github.com/leaanthony/u v1.1.1 // indirect
-	github.com/lmittmann/tint v1.0.4 // indirect
+	github.com/lmittmann/tint v1.0.7 // indirect
-	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-colorable v0.1.14 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
-	github.com/pjbgf/sha1cd v0.3.1 // indirect
+	github.com/pjbgf/sha1cd v0.3.2 // indirect
-	github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8 // indirect
+	github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
-	github.com/samber/lo v1.38.1 // indirect
+	github.com/samber/lo v1.49.1 // indirect
 	github.com/sergi/go-diff v1.3.2-0.20230802210424-5b0b94c5c0d3 // indirect
-	github.com/skeema/knownhosts v1.3.0 // indirect
+	github.com/skeema/knownhosts v1.3.1 // indirect
 	github.com/wailsapp/go-webview2 v1.0.19 // indirect
 	github.com/wailsapp/mimetype v1.4.1 // indirect
 	github.com/xanzy/ssh-agent v0.3.3 // indirect
-	golang.org/x/crypto v0.32.0 // indirect
+	golang.org/x/crypto v0.33.0 // indirect
-	golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56 // indirect
+	golang.org/x/exp v0.0.0-20250210185358-939b2ce775ac // indirect
-	golang.org/x/mod v0.22.0 // indirect
+	golang.org/x/mod v0.23.0 // indirect
-	golang.org/x/net v0.34.0 // indirect
+	golang.org/x/net v0.35.0 // indirect
-	golang.org/x/sync v0.10.0 // indirect
+	golang.org/x/sync v0.11.0 // indirect
-	golang.org/x/sys v0.29.0 // indirect
+	golang.org/x/sys v0.30.0 // indirect
-	golang.org/x/tools v0.29.0 // indirect
+	golang.org/x/tools v0.30.0 // indirect
 	gopkg.in/warnings.v0 v0.1.2 // indirect
 )
 

v3/examples/file-association/go.sum

@@ -8,6 +8,7 @@ github.com/Microsoft/go-winio v0.6.2/go.mod h1:yd8OoFMLzJbo9gZq8j5qaps8bJ9aShtEA
 github.com/ProtonMail/go-crypto v0.0.0-20230828082145-3c4c8a2d2371 h1:kkhsdkhsCvIsutKu5zLMgWtgh9YxGCNAw8Ad8hjwfYg=
 github.com/ProtonMail/go-crypto v0.0.0-20230828082145-3c4c8a2d2371/go.mod h1:EjAoLdwvbIOoOQr3ihjnSoLZRtE8azugULFRteWMNc0=
 github.com/ProtonMail/go-crypto v1.1.4/go.mod h1:rA3QumHc/FZ8pAHreoekgiAbzpNsfQAosU5td4SnOrE=
+github.com/ProtonMail/go-crypto v1.1.5/go.mod h1:rA3QumHc/FZ8pAHreoekgiAbzpNsfQAosU5td4SnOrE=
 github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be h1:9AeTilPcZAjCFIImctFaOjnTIavg87rW78vTPkQqLI8=
 github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be/go.mod h1:ySMOLuWl6zY27l47sB3qLNK6tF2fkHG55UZxx8oIVo4=
 github.com/armon/go-socks5 v0.0.0-20160902184237-e75332964ef5 h1:0CwZNZbxp69SHPdPJAN/hZIm0C4OItdklCFmMRWYpio=
@@ -19,14 +20,17 @@ github.com/cloudflare/circl v1.3.3/go.mod h1:5XYMA4rFBvNIrhs50XuiBJ15vF2pZn4nnUK
 github.com/cloudflare/circl v1.3.7 h1:qlCDlTPz2n9fu58M0Nh1J/JzcFpfgkFHHX3O35r5vcU=
 github.com/cloudflare/circl v1.3.7/go.mod h1:sRTcRWXGLrKw6yIGJ+l7amYJFfAXbZG0kBSc8r4zxgA=
 github.com/cloudflare/circl v1.5.0/go.mod h1:uddAzsPgqdMAYatqJ0lsjX1oECcQLIlRpzZh3pJrofs=
+github.com/cloudflare/circl v1.6.0/go.mod h1:uddAzsPgqdMAYatqJ0lsjX1oECcQLIlRpzZh3pJrofs=
 github.com/cyphar/filepath-securejoin v0.2.4 h1:Ugdm7cg7i6ZK6x3xDF1oEu1nfkyfH53EtKeQYTC3kyg=
 github.com/cyphar/filepath-securejoin v0.2.4/go.mod h1:aPGpWjXOXUn2NCNjFvBE6aRxGGx79pTxQpKOJNYHHl4=
 github.com/cyphar/filepath-securejoin v0.4.0/go.mod h1:Sdj7gXlvMcPZsbhwhQ33GguGLDGQL7h7bg04C/+u9jI=
+github.com/cyphar/filepath-securejoin v0.4.1/go.mod h1:Sdj7gXlvMcPZsbhwhQ33GguGLDGQL7h7bg04C/+u9jI=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/ebitengine/purego v0.4.0-alpha.4 h1:Y7yIV06Yo5M2BAdD7EVPhfp6LZ0tEcQo5770OhYUVes=
 github.com/ebitengine/purego v0.4.0-alpha.4/go.mod h1:ah1In8AOtksoNK6yk5z1HTJeUkC1Ez4Wk2idgGslMwQ=
+github.com/ebitengine/purego v0.8.2/go.mod h1:iIjxzd6CiRiOG0UyXP+V1+jWqUXVjPKLAI0mRfJZTmQ=
 github.com/elazarl/goproxy v0.0.0-20230808193330-2592e75ae04a h1:mATvB/9r/3gvcejNsXKSkQ6lcIaNec2nyfOdlTBR2lU=
 github.com/elazarl/goproxy v0.0.0-20230808193330-2592e75ae04a/go.mod h1:Ro8st/ElPeALwNFlcTpWmkr6IoMFfkjXAvTHpevnDsM=
 github.com/emirpasic/gods v1.18.1 h1:FXtiHYKDGKCW2KzwZKx0iC0PQmdlorYgdFG9jPXJ1Bc=
@@ -43,6 +47,7 @@ github.com/go-git/go-git-fixtures/v4 v4.3.2-0.20231010084843-55a94097c399/go.mod
 github.com/go-git/go-git/v5 v5.11.0 h1:XIZc1p+8YzypNr34itUfSvYJcv+eYdTnTvOZ2vD3cA4=
 github.com/go-git/go-git/v5 v5.11.0/go.mod h1:6GFcX2P3NM7FPBfpePbpLd21XxsgdAt+lKqXmCUiUCY=
 github.com/go-git/go-git/v5 v5.13.1/go.mod h1:qryJB4cSBoq3FRoBRf5A77joojuBcmPJ0qu3XXXVixc=
+github.com/go-git/go-git/v5 v5.13.2/go.mod h1:hWdW5P4YZRjmpGHwRH2v3zkWcNl6HeXaXQEMGb3NJ9A=
 github.com/go-ole/go-ole v1.2.6 h1:/Fpf6oFPoeFik9ty7siob0G6Ke8QvQEuVcuChpwXzpY=
 github.com/go-ole/go-ole v1.2.6/go.mod h1:pprOEPIfldk/42T2oK7lQ4v4JSDwmV0As9GaiUsvbm0=
 github.com/go-ole/go-ole v1.3.0/go.mod h1:5LS6F96DhAwUc7C+1HLexzMXY1xGRSryjyPPKW6zv78=
@@ -73,12 +78,15 @@ github.com/leaanthony/go-ansi-parser v1.6.1 h1:xd8bzARK3dErqkPFtoF9F3/HgN8UQk0ed
 github.com/leaanthony/go-ansi-parser v1.6.1/go.mod h1:+vva/2y4alzVmmIEpk9QDhA7vLC5zKDTRwfZGOp3IWU=
 github.com/leaanthony/u v1.1.0 h1:2n0d2BwPVXSUq5yhe8lJPHdxevE2qK5G99PMStMZMaI=
 github.com/leaanthony/u v1.1.0/go.mod h1:9+o6hejoRljvZ3BzdYlVL0JYCwtnAsVuN9pVTQcaRfI=
+github.com/leaanthony/u v1.1.1/go.mod h1:9+o6hejoRljvZ3BzdYlVL0JYCwtnAsVuN9pVTQcaRfI=
 github.com/lmittmann/tint v1.0.4 h1:LeYihpJ9hyGvE0w+K2okPTGUdVLfng1+nDNVR4vWISc=
 github.com/lmittmann/tint v1.0.4/go.mod h1:HIS3gSy7qNwGCj+5oRjAutErFBl4BzdQP6cJZ0NfMwE=
+github.com/lmittmann/tint v1.0.7/go.mod h1:HIS3gSy7qNwGCj+5oRjAutErFBl4BzdQP6cJZ0NfMwE=
 github.com/matryer/is v1.4.0 h1:sosSmIWwkYITGrxZ25ULNDeKiMNzFSr4V/eqBQP0PeE=
 github.com/matryer/is v1.4.0/go.mod h1:8I/i5uYgLzgsgEloJE1U6xx5HkBQpAZvepWuujKwMRU=
 github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
 github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
+github.com/mattn/go-colorable v0.1.14/go.mod h1:6LmQG8QLFO4G5z1gPvYEzlUgJ2wF+stgPZH1UqBm1s8=
 github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
 github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
 github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
@@ -87,8 +95,10 @@ github.com/onsi/gomega v1.27.10/go.mod h1:RsS8tutOdbdgzbPtzzATp12yT7kM5I5aElG3ev
 github.com/pjbgf/sha1cd v0.3.0 h1:4D5XXmUUBUl/xQ6IjCkEAbqXskkq/4O7LmGn0AqMDs4=
 github.com/pjbgf/sha1cd v0.3.0/go.mod h1:nZ1rrWOcGJ5uZgEEVL1VUM9iRQiZvWdbZjkKyFzPPsI=
 github.com/pjbgf/sha1cd v0.3.1/go.mod h1:Y8t7jSB/dEI/lQE04A1HVKteqjj9bX5O4+Cex0TCu8s=
+github.com/pjbgf/sha1cd v0.3.2/go.mod h1:zQWigSxVmsHEZow5qaLtPYxpcKMMQpa09ixqBxuCS6A=
 github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8 h1:KoWmjvw+nsYOo29YJK9vDA65RGE3NrOnUtO7a+RF9HU=
 github.com/pkg/browser v0.0.0-20210911075715-681adbf594b8/go.mod h1:HKlIX3XHQyzLZPlr7++PzdhaXEj94dEiJgZDTsxEqUI=
+github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c/go.mod h1:7rwL4CYBLnjLxUqIJNnCWiEdr3bn6IUYi15bNlnbCCU=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
@@ -100,6 +110,7 @@ github.com/rogpeppe/go-internal v1.11.0 h1:cWPaGQEPrBb5/AsnsZesgZZ9yb1OQ+GOISoDN
 github.com/rogpeppe/go-internal v1.11.0/go.mod h1:ddIwULY96R17DhadqLgMfk9H9tvdUzkipdSkR5nkCZA=
 github.com/samber/lo v1.38.1 h1:j2XEAqXKb09Am4ebOg31SpvzUTTs6EN3VfgeLUhPdXM=
 github.com/samber/lo v1.38.1/go.mod h1:+m/ZKRl6ClXCE2Lgf3MsQlWfh4bn1bz6CXEOxnEXnEA=
+github.com/samber/lo v1.49.1/go.mod h1:dO6KHFzUKXgP8LDhU0oI8d2hekjXnGOu0DB8Jecxd6o=
 github.com/sergi/go-diff v1.2.0 h1:XU+rvMAioB0UC3q1MFrIQy4Vo5/4VsRDQQXHsEya6xQ=
 github.com/sergi/go-diff v1.2.0/go.mod h1:STckp+ISIX8hZLjrqAeVduY0gWCT9IjLuqbuNXdaHfM=
 github.com/sergi/go-diff v1.3.2-0.20230802210424-5b0b94c5c0d3/go.mod h1:A0bzQcvG0E7Rwjx0REVgAGH58e96+X0MeOfepqsbeW4=
@@ -107,6 +118,7 @@ github.com/sirupsen/logrus v1.7.0/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic
 github.com/skeema/knownhosts v1.2.1 h1:SHWdIUa82uGZz+F+47k8SY4QhhI291cXCpopT1lK2AQ=
 github.com/skeema/knownhosts v1.2.1/go.mod h1:xYbVRSPxqBZFrdmDyMmsOs+uX1UZC3nTN3ThzgDxUwo=
 github.com/skeema/knownhosts v1.3.0/go.mod h1:sPINvnADmT/qYH1kfv+ePMmOBTH6Tbl7b5LvTDjFK7M=
+github.com/skeema/knownhosts v1.3.1/go.mod h1:r7KTdC8l4uxWRyK2TpQZ/1o5HaSzh06ePQNxPwTcfiY=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
@@ -128,14 +140,17 @@ golang.org/x/crypto v0.7.0/go.mod h1:pYwdfH91IfpZVANVyUOhSIPZaFoJGxTFbZhFTx+dXZU
 golang.org/x/crypto v0.23.0 h1:dIJU/v2J8Mdglj/8rJ6UUOM3Zc9zLZxVZwwxMooUSAI=
 golang.org/x/crypto v0.23.0/go.mod h1:CKFgDieR+mRhux2Lsu27y0fO304Db0wZe70UKqHu0v8=
 golang.org/x/crypto v0.32.0/go.mod h1:ZnnJkOaASj8g0AjIduWNlq2NRxL0PlBrbKVyZ6V/Ugc=
+golang.org/x/crypto v0.33.0/go.mod h1:bVdXmD7IV/4GdElGPozy6U7lWdRXA4qyRVGJV57uQ5M=
 golang.org/x/exp v0.0.0-20230626212559-97b1e661b5df h1:UA2aFVmmsIlefxMk29Dp2juaUSth8Pyn3Tq5Y5mJGME=
 golang.org/x/exp v0.0.0-20230626212559-97b1e661b5df/go.mod h1:FXUEEKJgO7OQYeo8N01OfiKP8RXMtf6e8aTskBGqWdc=
 golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56/go.mod h1:M4RDyNAINzryxdtnbRXRL/OHtkFuWGRjvuhBJpk2IlY=
+golang.org/x/exp v0.0.0-20250210185358-939b2ce775ac/go.mod h1:hH+7mtFmImwwcMvScyxUhjuVHR3HGaDPMn9rMSUUbxo=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
 golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
 golang.org/x/mod v0.17.0 h1:zY54UmvipHiNd+pm+m0x9KhZ9hl1/7QNMyxXbc6ICqA=
 golang.org/x/mod v0.17.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
 golang.org/x/mod v0.22.0/go.mod h1:6SkKJ3Xj0I0BrPOZoBy3bdMptDDU9oJrpohJ3eWZ1fY=
+golang.org/x/mod v0.23.0/go.mod h1:6SkKJ3Xj0I0BrPOZoBy3bdMptDDU9oJrpohJ3eWZ1fY=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/net v0.0.0-20210505024714-0287a6fb4125/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
@@ -147,12 +162,14 @@ golang.org/x/net v0.8.0/go.mod h1:QVkue5JL9kW//ek3r6jTKnTFis1tRmNAW2P1shuFdJc=
 golang.org/x/net v0.25.0 h1:d/OCCoBEUq33pjydKrGQhw7IlUPI2Oylr+8qLx49kac=
 golang.org/x/net v0.25.0/go.mod h1:JkAGAh7GEvH74S6FOH42FLoXpXbE/aqXSrIQjXgsiwM=
 golang.org/x/net v0.34.0/go.mod h1:di0qlW3YNM5oh6GqDGQr92MyTozJPmybPK4Ev/Gm31k=
+golang.org/x/net v0.35.0/go.mod h1:EglIi67kWsHKlRzzVMUD93VMSWGFOMSZgxFjparz1Qk=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.8.0 h1:3NFvSEYkUoMifnESzZl15y791HH1qU2xm6eCJU5ZPXQ=
 golang.org/x/sync v0.8.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sync v0.10.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sync v0.11.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190916202348-b4ddaad3f8a3/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -174,6 +191,7 @@ golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.20.0 h1:Od9JTbYCk261bKm4M/mw7AklTlFYIa0bIp9BgSm1S8Y=
 golang.org/x/sys v0.20.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/sys v0.29.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.2.0/go.mod h1:TVmDHMZPmdnySmBfhjOoOdhjzdE1h4u1VwSiw2l1Nuc=
@@ -197,6 +215,7 @@ golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
 golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d h1:vU5i/LfpvrRCpgM/VPfJLg5KjxD3E+hfT1SH+d9zLwg=
 golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d/go.mod h1:aiJjzUbINMkxbQROHiO6hDPo2LHcIPhhQsa9DLh0yGk=
 golang.org/x/tools v0.29.0/go.mod h1:KMQVMRsVxU6nHCFXrBPhDB8XncLNLM0lIy/F14RP588=
+golang.org/x/tools v0.30.0/go.mod h1:c347cR/OJfw5TI+GfX7RUPNMdDRRbjvYTS0jPyvsVtY=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

v3/internal/assetserver/assetserver.go

@@ -19,12 +19,15 @@ type RuntimeHandler interface {
 	HandleRuntimeCall(w http.ResponseWriter, r *http.Request)
 }
 
+type service struct {
+	Route   string
+	Handler http.Handler
+}
+
 type AssetServer struct {
-	options *Options
+	options  *Options
-
+	handler  http.Handler
-	handler http.Handler
+	services []service
-
-	services map[string]http.Handler
 
 	assetServerWebView
 }
@@ -112,11 +115,11 @@ func (a *AssetServer) serveHTTP(rw http.ResponseWriter, req *http.Request, userH
 		userHandler.ServeHTTP(wrapped, req)
 
 	default:
-		// Check if the path matches the keys in the services map
+		// Check if the path matches a service route
-		for route, handler := range a.services {
+		for _, svc := range a.services {
-			if strings.HasPrefix(reqPath, route) {
+			if strings.HasPrefix(reqPath, svc.Route) {
-				req.URL.Path = strings.TrimPrefix(reqPath, route)
+				req.URL.Path = strings.TrimPrefix(reqPath, svc.Route)
-				handler.ServeHTTP(rw, req)
+				svc.Handler.ServeHTTP(rw, req)
 				return
 			}
 		}
@@ -126,11 +129,8 @@ func (a *AssetServer) serveHTTP(rw http.ResponseWriter, req *http.Request, userH
 	}
 }
 
-func (a *AssetServer) AttachServiceHandler(prefix string, handler http.Handler) {
+func (a *AssetServer) AttachServiceHandler(route string, handler http.Handler) {
-	if a.services == nil {
+	a.services = append(a.services, service{route, handler})
-		a.services = make(map[string]http.Handler)
-	}
-	a.services[prefix] = handler
 }
 
 func (a *AssetServer) writeBlob(rw http.ResponseWriter, filename string, blob []byte) {

v3/internal/buildinfo/buildinfo.go

@@ -2,8 +2,10 @@ package buildinfo
 
 import (
 	"fmt"
-	"github.com/samber/lo"
 	"runtime/debug"
+	"slices"
+
+	"github.com/samber/lo"
 )
 
 type Info struct {
@@ -29,7 +31,9 @@ func Get() (*Info, error) {
 		return setting.Key, setting.Value
 	})
 	result.Version = BuildInfo.Main.Version
-	result.Development = BuildInfo.Main.Version == "(devel)"
+	result.Development = -1 != slices.IndexFunc(BuildInfo.Settings, func(setting debug.BuildSetting) bool {
+		return setting.Key == "vcs" && setting.Value == "git"
+	})
 
 	return &result, nil
 

v3/internal/commands/update_cli.go

@@ -2,14 +2,15 @@ package commands
 
 import (
 	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+
 	"github.com/pterm/pterm"
 	"github.com/wailsapp/wails/v3/internal/debug"
 	"github.com/wailsapp/wails/v3/internal/github"
 	"github.com/wailsapp/wails/v3/internal/term"
 	"github.com/wailsapp/wails/v3/internal/version"
-	"os"
-	"os/exec"
-	"path/filepath"
 )
 
 type UpdateCLIOptions struct {
@@ -31,9 +32,9 @@ func UpdateCLI(options *UpdateCLIOptions) error {
 		v3Path := filepath.ToSlash(debug.LocalModulePath + "/v3")
 		term.Println("This Wails CLI has been installed from source. To update to the latest stable release, run the following commands in the `" + v3Path + "` directory:")
 		term.Println("   - git pull")
-		term.Println("   - go install")
+		term.Println("   - wails3 task install")
 		term.Println("")
-		term.Println("If you want to install the latest release, please run `wails update cli -latest`")
+		term.Println("If you want to install the latest release, please run `wails3 update cli -latest`")
 		return nil
 	}
 
@@ -69,7 +70,7 @@ func UpdateCLI(options *UpdateCLIOptions) error {
 			if err != nil {
 				pterm.Println("")
 				pterm.Println("No stable release found for this major version. To update to the latest pre-release (eg beta), run:")
-				pterm.Println("   wails update -pre")
+				pterm.Println("   wails3 update cli -pre")
 				return nil
 			}
 		}
@@ -142,7 +143,7 @@ func updateToVersion(targetVersion *github.SemanticVersion, force bool, currentV
 		// Compare
 		if !success {
 			pterm.Println("Error: The requested version is lower than the current version.")
-			pterm.Printf("If this is what you really want to do, use `wails update -version %s`\n", targetVersionString)
+			pterm.Printf("If this is what you really want to do, use `wails3 update cli -version %s`\n", targetVersionString)
 			return nil
 		}
 

v3/internal/generator/collect/service.go

@@ -220,7 +220,7 @@ func (info *ServiceInfo) collectMethod(method *types.Func) *ServiceMethodInfo {
 	}
 
 	fqn := path + "." + obj.Name() + "." + method.Name()
-	id, _ := hash.Fnv(fqn)
+	id := hash.Fnv(fqn)
 
 	methodInfo := &ServiceMethodInfo{
 		MethodInfo: collector.Method(method).Collect(),
@@ -265,6 +265,7 @@ func (info *ServiceInfo) collectMethod(method *types.Func) *ServiceMethodInfo {
 					idValue,
 				)
 				methodInfo.ID = strconv.FormatUint(idValue, 10)
+				methodIdFound = true
 			}
 		}
 	}

v3/internal/hash/fnv.go

@@ -2,11 +2,8 @@ package hash
 
 import "hash/fnv"
 
-func Fnv(s string) (uint32, error) {
+func Fnv(s string) uint32 {
 	h := fnv.New32a()
-	_, err := h.Write([]byte(s))
+	_, _ = h.Write([]byte(s)) // Hash implementations never return errors (see https://pkg.go.dev/hash#Hash)
-	if err != nil {
+	return h.Sum32()
-		return 0, err
-	}
-	return h.Sum32(), nil
 }

v3/internal/runtime/Taskfile.yaml

@@ -12,10 +12,12 @@ tasks:
       - npm install
 
   test:
+    dir: desktop/@wailsio/runtime
     cmds:
       - npx vitest run
 
   update:
+    dir: desktop/@wailsio/runtime
     cmds:
       - npx npm-check-updates -u
 

v3/internal/runtime/desktop/@wailsio/runtime/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "@wailsio/runtime",
-  "version": "3.0.0-alpha.39",
+  "version": "3.0.0-alpha.55",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@wailsio/runtime",
-      "version": "3.0.0-alpha.39",
+      "version": "3.0.0-alpha.55",
       "license": "MIT",
       "devDependencies": {
         "rimraf": "^5.0.5",

v3/internal/runtime/desktop/@wailsio/runtime/src/calls.js

@@ -48,7 +48,17 @@ function generateID() {
 function resultHandler(id, data, isJSON) {
     const promiseHandler = getAndDeleteResponse(id);
     if (promiseHandler) {
-        promiseHandler.resolve(isJSON ? JSON.parse(data) : data);
+        if (!data) {
+            promiseHandler.resolve();
+        } else if (!isJSON) {
+            promiseHandler.resolve(data);
+        } else {
+            try {
+                promiseHandler.resolve(JSON.parse(data));
+            } catch (err) {
+                promiseHandler.reject(new TypeError("could not parse result: " + err.message, { cause: err }));
+            }
+        }
     }
 }
 
@@ -56,14 +66,48 @@ function resultHandler(id, data, isJSON) {
  * Handles the error from a call request.
  *
  * @param {string} id - The id of the promise handler.
- * @param {string} message - The error message to reject the promise handler with.
+ * @param {string} data - The error data to reject the promise handler with.
+ * @param {boolean} isJSON - Indicates whether the data is JSON or not.
  *
  * @return {void}
  */
-function errorHandler(id, message) {
+function errorHandler(id, data, isJSON) {
     const promiseHandler = getAndDeleteResponse(id);
     if (promiseHandler) {
-        promiseHandler.reject(message);
+        if (!isJSON) {
+            promiseHandler.reject(new Error(data));
+        } else {
+            let error;
+            try {
+                error = JSON.parse(data);
+            } catch (err) {
+                promiseHandler.reject(new TypeError("could not parse error: " + err.message, { cause: err }));
+                return;
+            }
+
+            let options = {};
+            if (error.cause) {
+                options.cause = error.cause;
+            }
+
+            let exception;
+            switch (error.kind) {
+                case "ReferenceError":
+                    exception = new ReferenceError(error.message, options);
+                    break;
+                case "TypeError":
+                    exception = new TypeError(error.message, options);
+                    break;
+                case "RuntimeError":
+                    exception = new RuntimeError(error.message, options);
+                    break;
+                default:
+                    exception = new Error(error.message, options);
+                    break;
+            }
+
+            promiseHandler.reject(exception);
+        }
     }
 }
 
@@ -81,30 +125,59 @@ function getAndDeleteResponse(id) {
 }
 
 /**
- * Executes a call using the provided type and options.
+ * Collects all required information for a binding call.
  *
- * @param {string|number} type - The type of call to execute.
+ * @typedef {Object} CallOptions
- * @param {Object} [options={}] - Additional options for the call.
+ * @property {number} [methodID] - The numeric ID of the bound method to call.
- * @return {Promise} - A promise that will be resolved or rejected based on the result of the call. It also has a cancel method to cancel a long running request.
+ * @property {string} [methodName] - The fully qualified name of the bound method to call.
+ * @property {any[]} args - Arguments to be passed into the bound method.
  */
-function callBinding(type, options = {}) {
+
+/**
+ * Exception class that will be thrown in case the bound method returns an error.
+ * The value of the {@link RuntimeError#name} property is "RuntimeError".
+ */
+export class RuntimeError extends Error {
+    /**
+     * Constructs a new RuntimeError instance.
+     *
+     * @param {string} message - The error message.
+     * @param {any[]} args - Optional arguments for the Error constructor.
+     */
+    constructor(message, ...args) {
+        super(message, ...args);
+        this.name = "RuntimeError";
+    }
+}
+
+/**
+ * Call a bound method according to the given call options.
+ *
+ * In case of failure, the returned promise will reject with an exception
+ * among ReferenceError (unknown method), TypeError (wrong argument count or type),
+ * {@link RuntimeError} (method returned an error), or other (network or internal errors).
+ * The exception might have a "cause" field with the value returned
+ * by the application- or service-level error marshaling functions.
+ *
+ * @param {CallOptions} options - A method call descriptor.
+ * @returns {Promise<any>} - The result of the call.
+ */
+export function Call(options) {
     const id = generateID();
     const doCancel = () => { return cancelCall(type, {"call-id": id}) };
     let queuedCancel = false, callRunning = false;
     let p = new Promise((resolve, reject) => {
         options["call-id"] = id;
         callResponses.set(id, { resolve, reject });
-        call(type, options).
+        call(CallBinding, options).then((_) => {
-            then((_) => {
+            callRunning = true;
-                callRunning = true;
+            if (queuedCancel) {
-                if (queuedCancel) {
+                return doCancel();
-                    return doCancel();
+            }
-                }
+        }).catch((error) => {
-            }).
+            reject(error);
-            catch((error) => {
+            callResponses.delete(id);
-                reject(error);
+        });
-                callResponses.delete(id);
-            });
     });
     p.cancel = () => {
         if (callRunning) {
@@ -118,57 +191,31 @@ function callBinding(type, options = {}) {
 }
 
 /**
- * Call method.
+ * Calls a bound method by name with the specified arguments.
- *
+ * See {@link Call} for details.
- * @param {Object} options - The options for the method.
- * @returns {Object} - The result of the call.
- */
-export function Call(options) {
-    return callBinding(CallBinding, options);
-}
-
-/**
- * Executes a method by name.
  *
  * @param {string} methodName - The name of the method in the format 'package.struct.method'.
- * @param {...*} args - The arguments to pass to the method.
+ * @param {any[]} args - The arguments to pass to the method.
- * @throws {Error} If the name is not a string or is not in the correct format.
+ * @returns {Promise<any>} The result of the method call.
- * @returns {*} The result of the method execution.
  */
 export function ByName(methodName, ...args) {
-    return callBinding(CallBinding, {
+    return Call({
         methodName,
         args
     });
 }
 
 /**
- * Calls a method by its ID with the specified arguments.
+ * Calls a method by its numeric ID with the specified arguments.
+ * See {@link Call} for details.
  *
  * @param {number} methodID - The ID of the method to call.
- * @param {...*} args - The arguments to pass to the method.
+ * @param {any[]} args - The arguments to pass to the method.
- * @return {*} - The result of the method call.
+ * @return {Promise<any>} - The result of the method call.
  */
 export function ByID(methodID, ...args) {
-    return callBinding(CallBinding, {
+    return Call({
         methodID,
         args
     });
 }
-
-/**
- * Calls a method on a plugin.
- *
- * @param {string} pluginName - The name of the plugin.
- * @param {string} methodName - The name of the method to call.
- * @param {...*} args - The arguments to pass to the method.
- * @returns {*} - The result of the method call.
- */
-export function Plugin(pluginName, methodName, ...args) {
-    return callBinding(CallBinding, {
-        packageName: "wails-plugins",
-        structName: pluginName,
-        methodName,
-        args
-    });
-}

v3/internal/runtime/desktop/@wailsio/runtime/src/dialogs.js

@@ -135,12 +135,12 @@ function dialog(type, options = {}) {
 function dialogResultCallback(id, data, isJSON) {
     let p = dialogResponses.get(id);
     if (p) {
+        dialogResponses.delete(id);
         if (isJSON) {
             p.resolve(JSON.parse(data));
         } else {
             p.resolve(data);
         }
-        dialogResponses.delete(id);
     }
 }
 
@@ -155,8 +155,8 @@ function dialogResultCallback(id, data, isJSON) {
 function dialogErrorCallback(id, message) {
     let p = dialogResponses.get(id);
     if (p) {
-        p.reject(message);
         dialogResponses.delete(id);
+        p.reject(new Error(message));
     }
 }
 

v3/internal/runtime/desktop/@wailsio/runtime/src/runtime.js

@@ -45,7 +45,7 @@ export function newRuntimeCaller(object, windowName) {
 /**
  * Creates a new runtime caller with specified ID.
  *
- * @param {object} object - The object to invoke the method on.
+ * @param {number} object - The object to invoke the method on.
  * @param {string} windowName - The name of the window.
  * @return {Function} - The new runtime caller function.
  */
@@ -57,8 +57,15 @@ export function newRuntimeCallerWithID(object, windowName) {
 
 
 function runtimeCall(method, windowName, args) {
+    return runtimeCallWithID(null, method, windowName, args);
+}
+
+async function runtimeCallWithID(objectID, method, windowName, args) {
     let url = new URL(runtimeURL);
-    if( method ) {
+    if (objectID != null) {
+        url.searchParams.append("object", objectID);
+    }
+    if (method != null) {
         url.searchParams.append("method", method);
     }
     let fetchOptions = {
@@ -72,52 +79,14 @@ function runtimeCall(method, windowName, args) {
     }
     fetchOptions.headers["x-wails-client-id"] = clientId;
 
-    return new Promise((resolve, reject) => {
+    let response = await fetch(url, fetchOptions);
-        fetch(url, fetchOptions)
+    if (!response.ok) {
-            .then(response => {
+        throw new Error(await response.text());
-                if (response.ok) {
+    }
-                    // check content type
-                    if (response.headers.get("Content-Type") && response.headers.get("Content-Type").indexOf("application/json") !== -1) {
-                        return response.json();
-                    } else {
-                        return response.text();
-                    }
-                }
-                reject(Error(response.statusText));
-            })
-            .then(data => resolve(data))
-            .catch(error => reject(error));
-    });
-}
 
-function runtimeCallWithID(objectID, method, windowName, args) {
+    if (response.headers.get("Content-Type") && response.headers.get("Content-Type").indexOf("application/json") !== -1) {
-    let url = new URL(runtimeURL);
+        return response.json();
-    url.searchParams.append("object", objectID);
+    } else {
-    url.searchParams.append("method", method);
+        return response.text();
-    let fetchOptions = {
-        headers: {},
-    };
-    if (windowName) {
-        fetchOptions.headers["x-wails-window-name"] = windowName;
     }
-    if (args) {
-        url.searchParams.append("args", JSON.stringify(args));
-    }
-    fetchOptions.headers["x-wails-client-id"] = clientId;
-    return new Promise((resolve, reject) => {
-        fetch(url, fetchOptions)
-            .then(response => {
-                if (response.ok) {
-                    // check content type
-                    if (response.headers.get("Content-Type") && response.headers.get("Content-Type").indexOf("application/json") !== -1) {
-                        return response.json();
-                    } else {
-                        return response.text();
-                    }
-                }
-                reject(Error(response.statusText));
-            })
-            .then(data => resolve(data))
-            .catch(error => reject(error));
-    });
 }

v3/internal/runtime/desktop/@wailsio/runtime/types/calls.d.ts

@@ -1,33 +1,69 @@
 /**
- * Call method.
+ * Call a bound method according to the given call options.
  *
- * @param {Object} options - The options for the method.
+ * In case of failure, the returned promise will reject with an exception
- * @returns {Object} - The result of the call.
+ * among ReferenceError (unknown method), TypeError (wrong argument count or type),
+ * {@link RuntimeError} (method returned an error), or other (network or internal errors).
+ * The exception might have a "cause" field with the value returned
+ * by the application- or service-level error marshaling functions.
+ *
+ * @param {CallOptions} options - A method call descriptor.
+ * @returns {Promise<any>} - The result of the call.
  */
-export function Call(options: any): any;
+export function Call(options: CallOptions): Promise<any>;
 /**
- * Executes a method by name.
+ * Calls a bound method by name with the specified arguments.
+ * See {@link Call} for details.
  *
  * @param {string} methodName - The name of the method in the format 'package.struct.method'.
- * @param {...*} args - The arguments to pass to the method.
+ * @param {any[]} args - The arguments to pass to the method.
- * @throws {Error} If the name is not a string or is not in the correct format.
+ * @returns {Promise<any>} The result of the method call.
- * @returns {*} The result of the method execution.
  */
-export function ByName(methodName: string, ...args: any[]): any;
+export function ByName(methodName: string, ...args: any[]): Promise<any>;
 /**
- * Calls a method by its ID with the specified arguments.
+ * Calls a method by its numeric ID with the specified arguments.
+ * See {@link Call} for details.
  *
  * @param {number} methodID - The ID of the method to call.
- * @param {...*} args - The arguments to pass to the method.
+ * @param {any[]} args - The arguments to pass to the method.
- * @return {*} - The result of the method call.
+ * @return {Promise<any>} - The result of the method call.
  */
-export function ByID(methodID: number, ...args: any[]): any;
+export function ByID(methodID: number, ...args: any[]): Promise<any>;
 /**
- * Calls a method on a plugin.
+ * Collects all required information for a binding call.
  *
- * @param {string} pluginName - The name of the plugin.
+ * @typedef {Object} CallOptions
- * @param {string} methodName - The name of the method to call.
+ * @property {number} [methodID] - The numeric ID of the bound method to call.
- * @param {...*} args - The arguments to pass to the method.
+ * @property {string} [methodName] - The fully qualified name of the bound method to call.
- * @returns {*} - The result of the method call.
+ * @property {any[]} args - Arguments to be passed into the bound method.
  */
-export function Plugin(pluginName: string, methodName: string, ...args: any[]): any;
+/**
+ * Exception class that will be thrown in case the bound method returns an error.
+ * The value of the {@link RuntimeError#name} property is "RuntimeError".
+ */
+export class RuntimeError extends Error {
+    /**
+     * Constructs a new RuntimeError instance.
+     *
+     * @param {string} message - The error message.
+     * @param {any[]} args - Optional arguments for the Error constructor.
+     */
+    constructor(message: string, ...args: any[]);
+}
+/**
+ * Collects all required information for a binding call.
+ */
+export type CallOptions = {
+    /**
+     * - The numeric ID of the bound method to call.
+     */
+    methodID?: number;
+    /**
+     * - The fully qualified name of the bound method to call.
+     */
+    methodName?: string;
+    /**
+     * - Arguments to be passed into the bound method.
+     */
+    args: any[];
+};

v3/internal/runtime/desktop/@wailsio/runtime/types/runtime.d.ts

@@ -9,11 +9,11 @@ export function newRuntimeCaller(object: any, windowName: string): Function;
 /**
  * Creates a new runtime caller with specified ID.
  *
- * @param {object} object - The object to invoke the method on.
+ * @param {number} object - The object to invoke the method on.
  * @param {string} windowName - The name of the window.
  * @return {Function} - The new runtime caller function.
  */
-export function newRuntimeCallerWithID(object: object, windowName: string): Function;
+export function newRuntimeCallerWithID(object: number, windowName: string): Function;
 export namespace objectNames {
     let Call: number;
     let Clipboard: number;

v3/internal/templates/_common/go.mod.tmpl

@@ -1,19 +1,51 @@
 module changeme
 
-go 1.21
+go 1.24
 
 require github.com/wailsapp/wails/v3 {{.WailsVersion}}
 
 require (
-    github.com/json-iterator/go v1.1.12 // indirect
+	dario.cat/mergo v1.0.1 // indirect
-    github.com/leaanthony/slicer v1.5.0 // indirect
+	github.com/Microsoft/go-winio v0.6.2 // indirect
-    github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421 // indirect
+	github.com/ProtonMail/go-crypto v1.1.5 // indirect
-    github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/adrg/xdg v0.5.3 // indirect
-    github.com/samber/lo v1.37.0 // indirect
+	github.com/bep/debounce v1.2.1 // indirect
-    github.com/wailsapp/mimetype v1.4.1 // indirect
+	github.com/cloudflare/circl v1.6.0 // indirect
-    golang.org/x/exp v0.0.0-20220930202632-ec3f01382ef9 // indirect
+	github.com/cyphar/filepath-securejoin v0.4.1 // indirect
-    golang.org/x/net v0.7.0 // indirect
+	github.com/ebitengine/purego v0.8.2 // indirect
+	github.com/emirpasic/gods v1.18.1 // indirect
+	github.com/go-git/gcfg v1.5.1-0.20230307220236-3a3c6141e376 // indirect
+	github.com/go-git/go-billy/v5 v5.6.2 // indirect
+	github.com/go-git/go-git/v5 v5.13.2 // indirect
+	github.com/go-ole/go-ole v1.3.0 // indirect
+	github.com/godbus/dbus/v5 v5.1.0 // indirect
+	github.com/golang/groupcache v0.0.0-20241129210726-2c02b8208cf8 // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99 // indirect
+	github.com/jchv/go-winloader v0.0.0-20210711035445-715c2860da7e // indirect
+	github.com/kevinburke/ssh_config v1.2.0 // indirect
+	github.com/leaanthony/go-ansi-parser v1.6.1 // indirect
+	github.com/leaanthony/u v1.1.1 // indirect
+	github.com/lmittmann/tint v1.0.7 // indirect
+	github.com/mattn/go-colorable v0.1.14 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/pjbgf/sha1cd v0.3.2 // indirect
+	github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/rivo/uniseg v0.4.7 // indirect
+	github.com/samber/lo v1.49.1 // indirect
+	github.com/sergi/go-diff v1.3.2-0.20230802210424-5b0b94c5c0d3 // indirect
+	github.com/skeema/knownhosts v1.3.1 // indirect
+	github.com/wailsapp/go-webview2 v1.0.19 // indirect
+	github.com/wailsapp/mimetype v1.4.1 // indirect
+	github.com/xanzy/ssh-agent v0.3.3 // indirect
+	golang.org/x/crypto v0.33.0 // indirect
+	golang.org/x/net v0.35.0 // indirect
+	golang.org/x/sys v0.30.0 // indirect
+	golang.org/x/text v0.22.0 // indirect
+	gopkg.in/ini.v1 v1.67.0 // indirect
+	gopkg.in/warnings.v0 v0.1.2 // indirect
 )
-{{if gt (len .LocalModulePath) 0}}
+{{if .LocalModulePath}}
 replace github.com/wailsapp/wails/v3 => {{.LocalModulePath}}v3
 {{end}}

v3/internal/templates/_common/go.sum.tmpl

@@ -1,33 +1,146 @@
+dario.cat/mergo v1.0.1 h1:Ra4+bf83h2ztPIQYNP99R6m+Y7KfnARDfID+a+vLl4s=
+dario.cat/mergo v1.0.1/go.mod h1:uNxQE+84aUszobStD9th8a29P2fMDhsBdgRYvZOxGmk=
+github.com/Microsoft/go-winio v0.5.2/go.mod h1:WpS1mjBmmwHBEWmogvA2mj8546UReBk4v8QkMxJ6pZY=
+github.com/Microsoft/go-winio v0.6.2 h1:F2VQgta7ecxGYO8k3ZZz3RS8fVIXVxONVUPlNERoyfY=
+github.com/Microsoft/go-winio v0.6.2/go.mod h1:yd8OoFMLzJbo9gZq8j5qaps8bJ9aShtEA8Ipt1oGCvU=
+github.com/ProtonMail/go-crypto v1.1.5 h1:eoAQfK2dwL+tFSFpr7TbOaPNUbPiJj4fLYwwGE1FQO4=
+github.com/ProtonMail/go-crypto v1.1.5/go.mod h1:rA3QumHc/FZ8pAHreoekgiAbzpNsfQAosU5td4SnOrE=
+github.com/adrg/xdg v0.5.3 h1:xRnxJXne7+oWDatRhR1JLnvuccuIeCoBu2rtuLqQB78=
+github.com/adrg/xdg v0.5.3/go.mod h1:nlTsY+NNiCBGCK2tpm09vRqfVzrc2fLmXGpBLF0zlTQ=
+github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be h1:9AeTilPcZAjCFIImctFaOjnTIavg87rW78vTPkQqLI8=
+github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be/go.mod h1:ySMOLuWl6zY27l47sB3qLNK6tF2fkHG55UZxx8oIVo4=
+github.com/armon/go-socks5 v0.0.0-20160902184237-e75332964ef5 h1:0CwZNZbxp69SHPdPJAN/hZIm0C4OItdklCFmMRWYpio=
+github.com/armon/go-socks5 v0.0.0-20160902184237-e75332964ef5/go.mod h1:wHh0iHkYZB8zMSxRWpUBQtwG5a7fFgvEO+odwuTv2gs=
+github.com/bep/debounce v1.2.1 h1:v67fRdBA9UQu2NhLFXrSg0Brw7CexQekrBwDMM8bzeY=
+github.com/bep/debounce v1.2.1/go.mod h1:H8yggRPQKLUhUoqrJC1bO2xNya7vanpDl7xR3ISbCJ0=
+github.com/cloudflare/circl v1.6.0 h1:cr5JKic4HI+LkINy2lg3W2jF8sHCVTBncJr5gIIq7qk=
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 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
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-github.com/json-iterator/go v1.1.12 h1:PV8peI4a0ysnczrg+LtxykD8LfKY9ML6u2jnxaEnrnM=
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-github.com/json-iterator/go v1.1.12/go.mod h1:e30LSqwooZae/UwlEbR2852Gd8hjQvJoHmT4TnhNGBo=
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 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
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v3/pkg/application/application.go

@@ -7,11 +7,11 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"log"
 	"log/slog"
 	"net/http"
 	"os"
 	"runtime"
+	"slices"
 	"strconv"
 	"strings"
 	"sync"
@@ -103,17 +103,17 @@ func New(appOptions Options) *App {
 					case "/wails/capabilities":
 						err := assetserver.ServeFile(rw, path, globalApplication.capabilities.AsBytes())
 						if err != nil {
-							result.handleFatalError(fmt.Errorf("unable to serve capabilities: %s", err.Error()))
+							result.fatal("unable to serve capabilities: %w", err)
 						}
 					case "/wails/flags":
 						updatedOptions := result.impl.GetFlags(appOptions)
 						flags, err := json.Marshal(updatedOptions)
 						if err != nil {
-							result.handleFatalError(fmt.Errorf("invalid flags provided to application: %s", err.Error()))
+							result.fatal("invalid flags provided to application: %w", err)
 						}
 						err = assetserver.ServeFile(rw, path, flags)
 						if err != nil {
-							result.handleFatalError(fmt.Errorf("unable to serve flags: %s", err.Error()))
+							result.fatal("unable to serve flags: %w", err)
 						}
 					default:
 						next.ServeHTTP(rw, req)
@@ -130,40 +130,14 @@ func New(appOptions Options) *App {
 
 	srv, err := assetserver.NewAssetServer(opts)
 	if err != nil {
-		result.handleFatalError(fmt.Errorf("Fatal error in application initialisation: " + err.Error()))
+		result.fatal("application initialisation failed: %w", err)
 	}
 
 	result.assets = srv
 	result.assets.LogDetails()
 
-	result.bindings, err = NewBindings(appOptions.Services, appOptions.BindAliases)
+	result.bindings = NewBindings(appOptions.MarshalError, appOptions.BindAliases)
-	if err != nil {
+	result.options.Services = slices.Clone(appOptions.Services)
-		result.handleFatalError(fmt.Errorf("Fatal error in application initialisation: " + err.Error()))
-	}
-
-	for i, service := range appOptions.Services {
-		if thisService, ok := service.instance.(ServiceStartup); ok {
-			err := thisService.ServiceStartup(result.ctx, service.options)
-			if err != nil {
-				name := service.options.Name
-				if name == "" {
-					name = getServiceName(service.instance)
-				}
-				globalApplication.Logger.Error("ServiceStartup() failed shutting down application:", "service", name, "error", err.Error())
-				// Run shutdown on all services that have already started
-				for _, service := range appOptions.Services[:i] {
-					if thisService, ok := service.instance.(ServiceShutdown); ok {
-						err := thisService.ServiceShutdown()
-						if err != nil {
-							globalApplication.Logger.Error("Error shutting down service: " + err.Error())
-						}
-					}
-				}
-				// Shutdown the application
-				os.Exit(1)
-			}
-		}
-	}
 
 	// Process keybindings
 	if result.options.KeyBindings != nil {
@@ -181,11 +155,11 @@ func New(appOptions Options) *App {
 			if errors.Is(err, alreadyRunningError) && manager != nil {
 				err = manager.notifyFirstInstance()
 				if err != nil {
-					globalApplication.error("Failed to notify first instance: " + err.Error())
+					globalApplication.error("failed to notify first instance: %w", err)
 				}
 				os.Exit(appOptions.SingleInstance.ExitCode)
 			}
-			result.handleFatalError(fmt.Errorf("failed to initialize single instance manager: %w", err))
+			result.fatal("failed to initialize single instance manager: %w", err)
 		} else {
 			result.singleInstanceManager = manager
 		}
@@ -314,7 +288,8 @@ type App struct {
 	menuItems     map[uint]*MenuItem
 	menuItemsLock sync.Mutex
 
-	// Running
+	// Starting and running
+	starting   bool
 	running    bool
 	runLock    sync.Mutex
 	pendingRun []runnable
@@ -350,7 +325,9 @@ type App struct {
 	keyBindingsLock sync.RWMutex
 
 	// Shutdown
-	performingShutdown bool
+	performingShutdown  bool
+	shutdownLock        sync.Mutex
+	serviceShutdownLock sync.Mutex
 
 	// Shutdown tasks are run when the application is shutting down.
 	// They are run in the order they are added and run on the main thread.
@@ -375,6 +352,7 @@ func (a *App) handleWarning(msg string) {
 		a.Logger.Warn(msg)
 	}
 }
+
 func (a *App) handleError(err error) {
 	if a.options.ErrorHandler != nil {
 		a.options.ErrorHandler(err)
@@ -383,6 +361,25 @@ func (a *App) handleError(err error) {
 	}
 }
 
+// RegisterService appends the given service to the list of bound services.
+// Registered services will be bound and initialised
+// in registration order upon calling [App.Run].
+//
+// RegisterService will log an error message
+// and discard the given service
+// if called after [App.Run].
+func (a *App) RegisterService(service Service) {
+	a.runLock.Lock()
+	defer a.runLock.Unlock()
+
+	if a.starting || a.running {
+		a.error("services must be registered before running the application. Service '%s' will not be registered.", getServiceName(service))
+		return
+	}
+
+	a.options.Services = append(a.options.Services, service)
+}
+
 // EmitEvent will emit an event
 func (a *App) EmitEvent(name string, data ...any) {
 	a.customEventProcessor.Emit(&CustomEvent{
@@ -417,13 +414,7 @@ func (a *App) ResetEvents() {
 }
 
 func (a *App) handleFatalError(err error) {
-	var buffer strings.Builder
+	a.handleError(&FatalError{err: err})
-	buffer.WriteString("\n\n************************ FATAL ******************************\n")
-	buffer.WriteString("* There has been a catastrophic failure in your application *\n")
-	buffer.WriteString("********************* Error Details *************************\n")
-	buffer.WriteString(err.Error())
-	buffer.WriteString("*************************************************************\n")
-	a.handleError(fmt.Errorf(buffer.String()))
 	os.Exit(1)
 }
 
@@ -587,6 +578,18 @@ func (a *App) NewSystemTray() *SystemTray {
 }
 
 func (a *App) Run() error {
+	a.runLock.Lock()
+	// Prevent double invocations.
+	if a.starting || a.running {
+		a.runLock.Unlock()
+		return errors.New("application is running or a previous run has failed")
+	}
+	// Block further service registrations.
+	a.starting = true
+	a.runLock.Unlock()
+
+	// Ensure application context is canceled in case of failures.
+	defer a.cancel()
 
 	// Call post-create hooks
 	err := a.preRun()
@@ -595,6 +598,24 @@ func (a *App) Run() error {
 	}
 
 	a.impl = newPlatformApp(a)
+
+	// Ensure services are shut down in case of failures.
+	defer a.shutdownServices()
+	// Ensure application context is canceled before service shutdown (duplicate calls don't hurt).
+	defer a.cancel()
+
+	// Startup services before dispatching any events.
+	// No need to hold the lock here because a.options.Services may only change when a.running is false.
+	services := a.options.Services
+	a.options.Services = nil
+	for i, service := range services {
+		if err := a.startupService(service); err != nil {
+			return fmt.Errorf("error starting service '%s': %w", getServiceName(service), err)
+		}
+		// Schedule started services for shutdown.
+		a.options.Services = services[:i+1]
+	}
+
 	go func() {
 		for {
 			event := <-applicationEvents
@@ -641,17 +662,19 @@ func (a *App) Run() error {
 
 	a.runLock.Lock()
 	a.running = true
+	a.runLock.Unlock()
 
-	for _, systray := range a.pendingRun {
+	// No need to hold the lock here because
+	//   - a.pendingRun may only change while a.running is false.
+	//   - runnables are scheduled asynchronously anyway.
+	for _, pending := range a.pendingRun {
 		go func() {
 			defer handlePanic()
-			systray.Run()
+			pending.Run()
 		}()
 	}
 	a.pendingRun = nil
 
-	a.runLock.Unlock()
-
 	// set the application menu
 	if runtime.GOOS == "darwin" {
 		a.impl.setApplicationMenu(a.ApplicationMenu)
@@ -660,27 +683,59 @@ func (a *App) Run() error {
 		a.impl.setIcon(a.options.Icon)
 	}
 
-	err = a.impl.run()
+	return a.impl.run()
+}
+
+func (a *App) startupService(service Service) error {
+	err := a.bindings.Add(service)
 	if err != nil {
-		return err
+		return fmt.Errorf("cannot bind service methods: %w", err)
 	}
 
-	// Cancel the context
+	if service.options.Route != "" {
-	a.cancel()
+		handler, ok := service.Instance().(http.Handler)
-
+		if !ok {
-	for _, service := range a.options.Services {
+			handler = http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
-		// If it conforms to the ServiceShutdown interface, call the Shutdown method
+				http.Error(
-		if thisService, ok := service.instance.(ServiceShutdown); ok {
+					rw,
-			err := thisService.ServiceShutdown()
+					fmt.Sprintf("Service '%s' does not handle HTTP requests", getServiceName(service)),
-			if err != nil {
+					http.StatusServiceUnavailable,
-				a.error("Error shutting down service: " + err.Error())
+				)
-			}
+			})
 		}
+		a.assets.AttachServiceHandler(service.options.Route, handler)
+	}
+
+	if s, ok := service.instance.(ServiceStartup); ok {
+		a.debug("Starting up service:", "name", getServiceName(service))
+		return s.ServiceStartup(a.ctx, service.options)
 	}
 
 	return nil
 }
 
+func (a *App) shutdownServices() {
+	// Acquire lock to prevent double calls (defer in Run() + OnShutdown)
+	a.serviceShutdownLock.Lock()
+	defer a.serviceShutdownLock.Unlock()
+
+	// Ensure app context is canceled first (duplicate calls don't hurt).
+	a.cancel()
+
+	for len(a.options.Services) > 0 {
+		last := len(a.options.Services) - 1
+		service := a.options.Services[last]
+		a.options.Services = a.options.Services[:last] // Prevent double shutdowns
+
+		if s, ok := service.instance.(ServiceShutdown); ok {
+			a.debug("Shutting down service:", "name", getServiceName(service))
+			if err := s.ServiceShutdown(); err != nil {
+				a.error("error shutting down service '%s': %w", getServiceName(service), err)
+			}
+		}
+	}
+}
+
 func (a *App) handleApplicationEvent(event *ApplicationEvent) {
 	defer handlePanic()
 	a.applicationEventListenersLock.RLock()
@@ -721,7 +776,7 @@ func (a *App) handleDragAndDropMessage(event *dragAndDropMessage) {
 	window, ok := a.windows[event.windowId]
 	a.windowsLock.Unlock()
 	if !ok {
-		log.Printf("WebviewWindow #%d not found", event.windowId)
+		a.warning("WebviewWindow #%d not found", event.windowId)
 		return
 	}
 	// Get callback from window
@@ -735,7 +790,7 @@ func (a *App) handleWindowMessage(event *windowMessage) {
 	window, ok := a.windows[event.windowId]
 	a.windowsLock.RUnlock()
 	if !ok {
-		log.Printf("WebviewWindow #%d not found", event.windowId)
+		a.warning("WebviewWindow #%d not found", event.windowId)
 		return
 	}
 	// Check if the message starts with "wails:"
@@ -760,7 +815,7 @@ func (a *App) handleWindowEvent(event *windowEvent) {
 	window, ok := a.windows[event.WindowID]
 	a.windowsLock.RUnlock()
 	if !ok {
-		log.Printf("Window #%d not found", event.WindowID)
+		a.warning("Window #%d not found", event.WindowID)
 		return
 	}
 	window.HandleWindowEvent(event.EventID)
@@ -771,7 +826,7 @@ func (a *App) handleMenuItemClicked(menuItemID uint) {
 
 	menuItem := getMenuItemByID(menuItemID)
 	if menuItem == nil {
-		log.Printf("MenuItem #%d not found", menuItemID)
+		a.warning("MenuItem #%d not found", menuItemID)
 		return
 	}
 	menuItem.handleClick()
@@ -796,7 +851,17 @@ func (a *App) OnShutdown(f func()) {
 	if f == nil {
 		return
 	}
-	a.shutdownTasks = append(a.shutdownTasks, f)
+
+	a.shutdownLock.Lock()
+
+	if !a.performingShutdown {
+		defer a.shutdownLock.Unlock()
+		a.shutdownTasks = append(a.shutdownTasks, f)
+		return
+	}
+
+	a.shutdownLock.Unlock()
+	InvokeAsync(f)
 }
 
 func (a *App) destroySystemTray(tray *SystemTray) {
@@ -808,14 +873,22 @@ func (a *App) destroySystemTray(tray *SystemTray) {
 }
 
 func (a *App) cleanup() {
+	a.shutdownLock.Lock()
 	if a.performingShutdown {
+		a.shutdownLock.Unlock()
 		return
 	}
+	a.cancel() // Cancel app context before running shutdown hooks.
 	a.performingShutdown = true
+	a.shutdownLock.Unlock()
+
+	// No need to hold the lock here because a.shutdownTasks
+	// may only change while a.performingShutdown is false.
 	for _, shutdownTask := range a.shutdownTasks {
 		InvokeSync(shutdownTask)
 	}
 	InvokeSync(func() {
+		a.shutdownServices()
 		a.windowsLock.RLock()
 		for _, window := range a.windows {
 			window.Close()
@@ -828,17 +901,23 @@ func (a *App) cleanup() {
 		}
 		a.systemTrays = nil
 		a.systemTraysLock.Unlock()
+
+		// Cleanup single instance manager
+		if a.singleInstanceManager != nil {
+			a.singleInstanceManager.cleanup()
+		}
+
+		a.postQuit()
+
+		if a.options.PostShutdown != nil {
+			a.options.PostShutdown()
+		}
 	})
-	// Cleanup single instance manager
-	if a.singleInstanceManager != nil {
-		a.singleInstanceManager.cleanup()
-	}
 }
 
 func (a *App) Quit() {
 	if a.impl != nil {
 		InvokeSync(a.impl.destroy)
-		a.postQuit()
 	}
 }
 
@@ -1006,15 +1085,17 @@ func (a *App) GetWindowByName(name string) Window {
 
 func (a *App) runOrDeferToAppRun(r runnable) {
 	a.runLock.Lock()
-	running := a.running
-	if !running {
-		a.pendingRun = append(a.pendingRun, r)
-	}
-	a.runLock.Unlock()
 
-	if running {
+	if !a.running {
-		r.Run()
+		defer a.runLock.Unlock() // Defer unlocking for panic tolerance.
+		a.pendingRun = append(a.pendingRun, r)
+		return
 	}
+
+	// Unlock immediately to prevent deadlocks.
+	// No TOC/TOU risk here because a.running can never switch back to false.
+	a.runLock.Unlock()
+	r.Run()
 }
 
 func (a *App) processKeyBinding(acceleratorString string, window *WebviewWindow) bool {
@@ -1056,7 +1137,7 @@ func (a *App) handleWindowKeyEvent(event *windowKeyEvent) {
 	window, ok := a.windows[event.windowId]
 	a.windowsLock.RUnlock()
 	if !ok {
-		log.Printf("WebviewWindow #%d not found", event.windowId)
+		a.warning("WebviewWindow #%d not found", event.windowId)
 		return
 	}
 	// Get callback from window

v3/pkg/application/application_darwin.go

@@ -362,7 +362,7 @@ func cleanup() {
 func (a *App) logPlatformInfo() {
 	info, err := operatingsystem.Info()
 	if err != nil {
-		a.error("Error getting OS info: %s", err.Error())
+		a.error("error getting OS info: %w", err)
 		return
 	}
 

v3/pkg/application/application_dev.go

@@ -3,9 +3,10 @@
 package application
 
 import (
-	"github.com/wailsapp/wails/v3/internal/assetserver"
 	"net/http"
 	"time"
+
+	"github.com/wailsapp/wails/v3/internal/assetserver"
 )
 
 var devMode = false

v3/pkg/application/application_linux.go

@@ -208,7 +208,7 @@ func newPlatformApp(parent *App) *linuxApp {
 func (a *App) logPlatformInfo() {
 	info, err := operatingsystem.Info()
 	if err != nil {
-		a.error("Error getting OS info: %s", err.Error())
+		a.error("error getting OS info: %w", err)
 		return
 	}
 

v3/pkg/application/application_options.go

@@ -31,11 +31,21 @@ type Options struct {
 	// Services allows you to bind Go methods to the frontend.
 	Services []Service
 
+	// MarshalError will be called if non-nil
+	// to marshal to JSON the error values returned by service methods.
+	//
+	// MarshalError is not allowed to fail,
+	// but it may return a nil slice to fall back
+	// to the default error handling mechanism.
+	//
+	// If the returned slice is not nil, it must contain valid JSON.
+	MarshalError func(error) []byte
+
 	// BindAliases allows you to specify alias IDs for your bound methods.
 	// Example: `BindAliases: map[uint32]uint32{1: 1411160069}` states that alias ID 1 maps to the Go method with ID 1411160069.
 	BindAliases map[uint32]uint32
 
-	// Logger i a slog.Logger instance used for logging Wails system messages (not application messages).
+	// Logger is a slog.Logger instance used for logging Wails system messages (not application messages).
 	// If not defined, a default logger is used.
 	Logger *slog.Logger
 
@@ -60,9 +70,17 @@ type Options struct {
 
 	// OnShutdown is called when the application is about to terminate.
 	// This is useful for cleanup tasks.
-	// The shutdown process blocks until this function returns
+	// The shutdown process blocks until this function returns.
 	OnShutdown func()
 
+	// PostShutdown is called after the application
+	// has finished shutting down, just before process termination.
+	// This is useful for testing and logging purposes
+	// on platforms where the Run() method does not return.
+	// When PostShutdown is called, the application instance is not usable anymore.
+	// The shutdown process blocks until this function returns.
+	PostShutdown func()
+
 	// ShouldQuit is a function that is called when the user tries to quit the application.
 	// If the function returns true, the application will quit.
 	// If the function returns false, the application will not quit.

v3/pkg/application/application_windows.go

@@ -3,7 +3,7 @@
 package application
 
 import (
-	"fmt"
+	"errors"
 	"os"
 	"path/filepath"
 	"slices"
@@ -215,7 +215,7 @@ func (m *windowsApp) wndProc(hwnd w32.HWND, msg uint32, wParam, lParam uintptr)
 		if msg == w32.WM_DISPLAYCHANGE || (msg == w32.WM_SETTINGCHANGE && wParam == w32.SPI_SETWORKAREA) {
 			err := m.processAndCacheScreens()
 			if err != nil {
-				m.parent.error(err.Error())
+				m.parent.handleError(err)
 			}
 		}
 	}
@@ -318,14 +318,14 @@ func setupDPIAwareness() error {
 		return w32.SetProcessDPIAware()
 	}
 
-	return fmt.Errorf("no DPI awareness method supported")
+	return errors.New("no DPI awareness method supported")
 }
 
 func newPlatformApp(app *App) *windowsApp {
 
 	err := setupDPIAwareness()
 	if err != nil {
-		app.error(err.Error())
+		app.handleError(err)
 	}
 
 	result := &windowsApp{
@@ -337,7 +337,7 @@ func newPlatformApp(app *App) *windowsApp {
 
 	err = result.processAndCacheScreens()
 	if err != nil {
-		app.fatal(err.Error())
+		app.handleFatalError(err)
 	}
 
 	result.init()

v3/pkg/application/bindings.go

@@ -5,7 +5,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"net/http"
 	"reflect"
 	"runtime"
 	"strings"
@@ -21,16 +20,22 @@ type CallOptions struct {
 	Args       []json.RawMessage `json:"args"`
 }
 
-type PluginCallOptions struct {
+type ErrorKind string
-	Name string            `json:"name"`
+
-	Args []json.RawMessage `json:"args"`
+const (
+	ReferenceError ErrorKind = "ReferenceError"
+	TypeError      ErrorKind = "TypeError"
+	RuntimeError   ErrorKind = "RuntimeError"
+)
+
+type CallError struct {
+	Kind    ErrorKind `json:"kind"`
+	Message string    `json:"message"`
+	Cause   any       `json:"cause,omitempty"`
 }
 
-var reservedPluginMethods = []string{
+func (e *CallError) Error() string {
-	"Name",
+	return e.Message
-	"Init",
-	"Shutdown",
-	"Exported",
 }
 
 // Parameter defines a Go method parameter
@@ -61,66 +66,75 @@ func (p *Parameter) IsError() bool {
 // BoundMethod defines all the data related to a Go method that is
 // bound to the Wails application
 type BoundMethod struct {
-	ID          uint32        `json:"id"`
+	ID       uint32        `json:"id"`
-	Name        string        `json:"name"`
+	Name     string        `json:"name"`
-	Inputs      []*Parameter  `json:"inputs,omitempty"`
+	Inputs   []*Parameter  `json:"inputs,omitempty"`
-	Outputs     []*Parameter  `json:"outputs,omitempty"`
+	Outputs  []*Parameter  `json:"outputs,omitempty"`
-	Comments    string        `json:"comments,omitempty"`
+	Comments string        `json:"comments,omitempty"`
-	Method      reflect.Value `json:"-"`
+	Method   reflect.Value `json:"-"`
-	TypeName    string
+	FQN      string
-	PackagePath string
 
+	marshalError func(error) []byte
 	needsContext bool
 }
 
 type Bindings struct {
+	marshalError  func(error) []byte
 	boundMethods  map[string]*BoundMethod
 	boundByID     map[uint32]*BoundMethod
 	methodAliases map[uint32]uint32
 }
 
-func NewBindings(instances []Service, aliases map[uint32]uint32) (*Bindings, error) {
+func NewBindings(marshalError func(error) []byte, aliases map[uint32]uint32) *Bindings {
-	app := Get()
+	return &Bindings{
-	b := &Bindings{
+		marshalError:  wrapErrorMarshaler(marshalError, defaultMarshalError),
 		boundMethods:  make(map[string]*BoundMethod),
 		boundByID:     make(map[uint32]*BoundMethod),
 		methodAliases: aliases,
 	}
-	for _, binding := range instances {
-		handler, ok := binding.Instance().(http.Handler)
-		if ok && binding.options.Route != "" {
-			app.assets.AttachServiceHandler(binding.options.Route, handler)
-		}
-		err := b.Add(binding.Instance())
-		if err != nil {
-			return nil, err
-		}
-	}
-	return b, nil
 }
 
-// Add the given named type pointer methods to the Bindings
+// Add adds the given service to the bindings.
-func (b *Bindings) Add(namedPtr interface{}) error {
+func (b *Bindings) Add(service Service) error {
-	methods, err := b.getMethods(namedPtr)
+	methods, err := getMethods(service.Instance())
 	if err != nil {
-		return fmt.Errorf("cannot bind value to app: %s", err.Error())
+		return err
+	}
+
+	marshalError := wrapErrorMarshaler(service.options.MarshalError, defaultMarshalError)
+
+	// Validate and log methods.
+	for _, method := range methods {
+		if _, ok := b.boundMethods[method.FQN]; ok {
+			return fmt.Errorf("bound method '%s' is already registered. Please note that you can register at most one service of each type; additional instances must be wrapped in dedicated structs", method.FQN)
+		}
+		if boundMethod, ok := b.boundByID[method.ID]; ok {
+			return fmt.Errorf("oh wow, we're sorry about this! Amazingly, a hash collision was detected for method '%s' (it generates the same hash as '%s'). To use this method, please rename it. Sorry :(", method.FQN, boundMethod.FQN)
+		}
+
+		// Log
+		attrs := []any{"fqn", method.FQN, "id", method.ID}
+		if alias, ok := lo.FindKey(b.methodAliases, method.ID); ok {
+			attrs = append(attrs, "alias", alias)
+		}
+		globalApplication.debug("Registering bound method:", attrs...)
 	}
 
 	for _, method := range methods {
-		// Add it as a regular method
+		// Store composite error marshaler
-		b.boundMethods[method.String()] = method
+		method.marshalError = marshalError
+
+		// Register method
+		b.boundMethods[method.FQN] = method
 		b.boundByID[method.ID] = method
 	}
+
 	return nil
 }
 
 // Get returns the bound method with the given name
 func (b *Bindings) Get(options *CallOptions) *BoundMethod {
-	method, ok := b.boundMethods[options.MethodName]
+	return b.boundMethods[options.MethodName]
-	if !ok {
-		return nil
-	}
-	return method
 }
 
 // GetByID returns the bound method with the given ID
@@ -131,29 +145,27 @@ func (b *Bindings) GetByID(id uint32) *BoundMethod {
 			id = alias
 		}
 	}
-	result := b.boundByID[id]
+
-	return result
+	return b.boundByID[id]
 }
 
-// GenerateID generates a unique ID for a binding
+// internalServiceMethod is a set of methods
-func (b *Bindings) GenerateID(name string) (uint32, error) {
+// that are handled specially by the binding engine
-	id, err := hash.Fnv(name)
+// and must not be exposed to the frontend.
-	if err != nil {
+//
-		return 0, err
+// For simplicity we exclude these by name
-	}
+// without checking their signatures,
-	// Check if we already have it
+// and so does the binding generator.
-	boundMethod, ok := b.boundByID[id]
+var internalServiceMethods = map[string]bool{
-	if ok {
+	"ServiceName":     true,
-		return 0, fmt.Errorf("oh wow, we're sorry about this! Amazingly, a hash collision was detected for method '%s' (it generates the same hash as '%s'). To continue, please rename it. Sorry :(", name, boundMethod.String())
+	"ServiceStartup":  true,
-	}
+	"ServiceShutdown": true,
-	return id, nil
+	"ServeHTTP":       true,
 }
 
-func (b *BoundMethod) String() string {
+var ctxType = reflect.TypeFor[context.Context]()
-	return fmt.Sprintf("%s.%s.%s", b.PackagePath, b.TypeName, b.Name)
-}
 
-func (b *Bindings) getMethods(value interface{}) ([]*BoundMethod, error) {
+func getMethods(value any) ([]*BoundMethod, error) {
 	// Create result placeholder
 	var result []*BoundMethod
 
@@ -180,42 +192,27 @@ func (b *Bindings) getMethods(value interface{}) ([]*BoundMethod, error) {
 		return nil, fmt.Errorf("%s.%s is a generic type. Generic bound types are not supported", packagePath, namedType.String())
 	}
 
-	ctxType := reflect.TypeFor[context.Context]()
-
 	// Process Methods
-	for i := 0; i < ptrType.NumMethod(); i++ {
+	for i := range ptrType.NumMethod() {
-		methodDef := ptrType.Method(i)
+		methodName := ptrType.Method(i).Name
-		methodName := methodDef.Name
+		method := namedValue.Method(i)
-		method := namedValue.MethodByName(methodName)
 
-		if b.internalMethod(methodDef) {
+		if internalServiceMethods[methodName] {
 			continue
 		}
 
+		fqn := fmt.Sprintf("%s.%s.%s", packagePath, typeName, methodName)
+
 		// Create new method
 		boundMethod := &BoundMethod{
-			Name:        methodName,
+			ID:       hash.Fnv(fqn),
-			PackagePath: packagePath,
+			FQN:      fqn,
-			TypeName:    typeName,
+			Name:     methodName,
-			Inputs:      nil,
+			Inputs:   nil,
-			Outputs:     nil,
+			Outputs:  nil,
-			Comments:    "",
+			Comments: "",
-			Method:      method,
+			Method:   method,
 		}
-		var err error
-		boundMethod.ID, err = b.GenerateID(boundMethod.String())
-		if err != nil {
-			return nil, err
-		}
-
-		args := []any{"name", boundMethod, "id", boundMethod.ID}
-		if b.methodAliases != nil {
-			alias, found := lo.FindKey(b.methodAliases, boundMethod.ID)
-			if found {
-				args = append(args, "alias", alias)
-			}
-		}
-		globalApplication.debug("Adding method:", args...)
 
 		// Iterate inputs
 		methodType := method.Type()
@@ -245,40 +242,23 @@ func (b *Bindings) getMethods(value interface{}) ([]*BoundMethod, error) {
 		result = append(result, boundMethod)
 
 	}
+
 	return result, nil
 }
 
-func (b *Bindings) internalMethod(def reflect.Method) bool {
+func (b *BoundMethod) String() string {
-	// Get the receiver type
+	return b.FQN
-	receiverType := def.Type.In(0)
-
-	// Create a new instance of the receiver type
-	instance := reflect.New(receiverType.Elem()).Interface()
-
-	// Check if the instance implements any of our service interfaces
-	// and if the method matches the interface method
-	switch def.Name {
-	case "ServiceName":
-		if _, ok := instance.(ServiceName); ok {
-			return true
-		}
-	case "ServiceStartup":
-		if _, ok := instance.(ServiceStartup); ok {
-			return true
-		}
-	case "ServiceShutdown":
-		if _, ok := instance.(ServiceShutdown); ok {
-			return true
-		}
-	}
-
-	return false
 }
 
 var errorType = reflect.TypeFor[error]()
 
-// Call will attempt to call this bound method with the given args
+// Call will attempt to call this bound method with the given args.
-func (b *BoundMethod) Call(ctx context.Context, args []json.RawMessage) (returnValue interface{}, err error) {
+// If the call succeeds, result will be either a non-error return value (if there is only one)
+// or a slice of non-error return values (if there are more than one).
+//
+// If the arguments are mistyped or the call returns one or more non-nil error values,
+// result is nil and err is an instance of *[CallError].
+func (b *BoundMethod) Call(ctx context.Context, args []json.RawMessage) (result any, err error) {
 	// Use a defer statement to capture panics
 	defer handlePanic(handlePanicOptions{skipEnd: 5})
 	argCount := len(args)
@@ -287,7 +267,10 @@ func (b *BoundMethod) Call(ctx context.Context, args []json.RawMessage) (returnV
 	}
 
 	if argCount != len(b.Inputs) {
-		err = fmt.Errorf("%s expects %d arguments, received %d", b.Name, len(b.Inputs), argCount)
+		err = &CallError{
+			Kind:    TypeError,
+			Message: fmt.Sprintf("%s expects %d arguments, got %d", b.FQN, len(b.Inputs), argCount),
+		}
 		return
 	}
 
@@ -305,7 +288,11 @@ func (b *BoundMethod) Call(ctx context.Context, args []json.RawMessage) (returnV
 		value := reflect.New(b.Inputs[base+index].ReflectType)
 		err = json.Unmarshal(arg, value.Interface())
 		if err != nil {
-			err = fmt.Errorf("could not parse argument #%d: %w", index, err)
+			err = &CallError{
+				Kind:    TypeError,
+				Message: fmt.Sprintf("could not parse argument #%d: %s", index, err),
+				Cause:   json.RawMessage(b.marshalError(err)),
+			}
 			return
 		}
 		callArgs[base+index] = value.Elem()
@@ -322,32 +309,73 @@ func (b *BoundMethod) Call(ctx context.Context, args []json.RawMessage) (returnV
 	var nonErrorOutputs = make([]any, 0, len(callResults))
 	var errorOutputs []error
 
-	for _, result := range callResults {
+	for _, field := range callResults {
-		if result.Type() == errorType {
+		if field.Type() == errorType {
-			if result.IsNil() {
+			if field.IsNil() {
 				continue
 			}
 			if errorOutputs == nil {
 				errorOutputs = make([]error, 0, len(callResults)-len(nonErrorOutputs))
 				nonErrorOutputs = nil
 			}
-			errorOutputs = append(errorOutputs, result.Interface().(error))
+			errorOutputs = append(errorOutputs, field.Interface().(error))
 		} else if nonErrorOutputs != nil {
-			nonErrorOutputs = append(nonErrorOutputs, result.Interface())
+			nonErrorOutputs = append(nonErrorOutputs, field.Interface())
 		}
 	}
 
-	if errorOutputs != nil {
+	if len(errorOutputs) > 0 {
-		err = errors.Join(errorOutputs...)
+		info := make([]json.RawMessage, len(errorOutputs))
+		for i, err := range errorOutputs {
+			info[i] = b.marshalError(err)
+		}
+
+		cerr := &CallError{
+			Kind:    RuntimeError,
+			Message: errors.Join(errorOutputs...).Error(),
+			Cause:   info,
+		}
+		if len(info) == 1 {
+			cerr.Cause = info[0]
+		}
+
+		err = cerr
 	} else if len(nonErrorOutputs) == 1 {
-		returnValue = nonErrorOutputs[0]
+		result = nonErrorOutputs[0]
 	} else if len(nonErrorOutputs) > 1 {
-		returnValue = nonErrorOutputs
+		result = nonErrorOutputs
 	}
 
 	return
 }
 
+// wrapErrorMarshaler returns an error marshaling functions
+// that calls the primary marshaler first,
+// then falls back to the secondary one.
+func wrapErrorMarshaler(primary func(error) []byte, secondary func(error) []byte) func(error) []byte {
+	if primary == nil {
+		return secondary
+	}
+
+	return func(err error) []byte {
+		result := primary(err)
+		if result == nil {
+			result = secondary(err)
+		}
+
+		return result
+	}
+}
+
+// defaultMarshalError implements the default error marshaling mechanism.
+func defaultMarshalError(err error) []byte {
+	result, jsonErr := json.Marshal(&err)
+	if jsonErr != nil {
+		return nil
+	}
+	return result
+}
+
 // isPtr returns true if the value given is a pointer.
 func isPtr(value interface{}) bool {
 	return reflect.ValueOf(value).Kind() == reflect.Ptr

v3/pkg/application/bindings_test.go

@@ -44,7 +44,7 @@ func (t *TestService) Variadic(s ...string) []string {
 	return s
 }
 
-func (t *TestService) PositionalAndVariadic(a int, b ...string) int {
+func (t *TestService) PositionalAndVariadic(a int, _ ...string) int {
 	return a
 }
 
@@ -52,106 +52,103 @@ func (t *TestService) Slice(a []int) []int {
 	return a
 }
 
-func newArgs(jsonArgs ...string) []json.RawMessage {
+func newArgs(jsonArgs ...string) (args []json.RawMessage) {
-	args := []json.RawMessage{}
-
 	for _, j := range jsonArgs {
 		args = append(args, json.RawMessage(j))
 	}
-	return args
+	return
 }
 
 func TestBoundMethodCall(t *testing.T) {
-
 	tests := []struct {
 		name     string
 		method   string
 		args     []json.RawMessage
-		err      error
+		err      string
 		expected interface{}
 	}{
 		{
 			name:     "nil",
 			method:   "Nil",
 			args:     []json.RawMessage{},
-			err:      nil,
+			err:      "",
 			expected: nil,
 		},
 		{
 			name:     "string",
 			method:   "String",
 			args:     newArgs(`"foo"`),
-			err:      nil,
+			err:      "",
 			expected: "foo",
 		},
 		{
 			name:     "multiple",
 			method:   "Multiple",
 			args:     newArgs(`"foo"`, "0", "false"),
-			err:      nil,
+			err:      "",
 			expected: []interface{}{"foo", 0, false},
 		},
 		{
 			name:     "struct",
 			method:   "Struct",
 			args:     newArgs(`{ "name": "alice" }`),
-			err:      nil,
+			err:      "",
 			expected: Person{Name: "alice"},
 		},
 		{
 			name:     "struct, nil error",
 			method:   "StructNil",
 			args:     newArgs(`{ "name": "alice" }`),
-			err:      nil,
+			err:      "",
 			expected: Person{Name: "alice"},
 		},
 		{
 			name:     "struct, error",
 			method:   "StructError",
 			args:     newArgs(`{ "name": "alice" }`),
-			err:      errors.New("error"),
+			err:      "error",
 			expected: nil,
 		},
 		{
 			name:     "invalid argument count",
 			method:   "Multiple",
 			args:     newArgs(`"foo"`),
-			err:      errors.New("expects 3 arguments, received 1"),
+			err:      "expects 3 arguments, got 1",
 			expected: nil,
 		},
 		{
 			name:     "invalid argument type",
 			method:   "String",
 			args:     newArgs("1"),
-			err:      errors.New("could not parse"),
+			err:      "could not parse",
 			expected: nil,
 		},
 		{
 			name:     "variadic, no arguments",
 			method:   "Variadic",
 			args:     newArgs(`[]`), // variadic parameters are passed as arrays
-			err:      nil,
+			err:      "",
 			expected: []string{},
 		},
 		{
 			name:     "variadic",
 			method:   "Variadic",
 			args:     newArgs(`["foo", "bar"]`),
-			err:      nil,
+			err:      "",
 			expected: []string{"foo", "bar"},
 		},
 		{
 			name:     "positional and variadic",
 			method:   "PositionalAndVariadic",
 			args:     newArgs("42", `[]`),
-			err:      nil,
+			err:      "",
 			expected: 42,
 		},
 		{
 			name:     "slice",
 			method:   "Slice",
 			args:     newArgs(`[1,2,3]`),
-			err:      nil,
+			err:      "",
 			expected: []int{1, 2, 3},
 		},
 	}
@@ -159,13 +156,11 @@ func TestBoundMethodCall(t *testing.T) {
 	// init globalApplication
 	_ = application.New(application.Options{})
 
-	bindings, err := application.NewBindings(
+	bindings := application.NewBindings(nil, nil)
-		[]application.Service{
+
-			application.NewService(&TestService{}),
+	err := bindings.Add(application.NewService(&TestService{}))
-		}, make(map[uint32]uint32),
-	)
 	if err != nil {
-		t.Fatalf("application.NewBindings() error = %v\n", err)
+		t.Fatalf("bindings.Add() error = %v\n", err)
 	}
 
 	for _, tt := range tests {
@@ -180,13 +175,16 @@ func TestBoundMethodCall(t *testing.T) {
 			}
 
 			result, err := method.Call(context.TODO(), tt.args)
-			if tt.err != err && (tt.err == nil || err == nil || !strings.Contains(err.Error(), tt.err.Error())) {
+			if (tt.err == "") != (err == nil) || (err != nil && !strings.Contains(err.Error(), tt.err)) {
-				t.Fatalf("error: %v, expected error: %v", err, tt.err)
+				expected := tt.err
+				if expected == "" {
+					expected = "nil"
+				}
+				t.Fatalf("error: %#v, expected error: %v", err, expected)
 			}
 			if !reflect.DeepEqual(result, tt.expected) {
 				t.Fatalf("result: %v, expected result: %v", result, tt.expected)
 			}
-
 		})
 	}
 

v3/pkg/application/dialogs_windows.go

@@ -42,7 +42,7 @@ func (m *windowsDialog) show() {
 	if m.dialog.window != nil {
 		parentWindow, err = m.dialog.window.NativeWindowHandle()
 		if err != nil {
-			globalApplication.fatal(err.Error())
+			globalApplication.handleFatalError(err)
 		}
 	}
 
@@ -50,12 +50,12 @@ func (m *windowsDialog) show() {
 		// 3 is the application icon
 		button, err = w32.MessageBoxWithIcon(parentWindow, message, title, 3, windows.MB_OK|windows.MB_USERICON)
 		if err != nil {
-			globalApplication.fatal(err.Error())
+			globalApplication.handleFatalError(err)
 		}
 	} else {
 		button, err = windows.MessageBox(windows.HWND(parentWindow), message, title, flags|windows.MB_SYSTEMMODAL)
 		if err != nil {
-			globalApplication.fatal(err.Error())
+			globalApplication.handleFatalError(err)
 		}
 	}
 	// This maps MessageBox return values to strings
@@ -114,7 +114,7 @@ func (m *windowOpenFileDialog) show() (chan string, error) {
 	if m.dialog.window != nil {
 		config.ParentWindowHandle, err = m.dialog.window.NativeWindowHandle()
 		if err != nil {
-			globalApplication.fatal(err.Error())
+			globalApplication.handleFatalError(err)
 		}
 	}
 
@@ -242,7 +242,7 @@ func showCfdDialog(newDlg func() (cfd.Dialog, error), isMultiSelect bool) (any,
 	defer func() {
 		err := dlg.Release()
 		if err != nil {
-			globalApplication.error("Unable to release dialog: " + err.Error())
+			globalApplication.error("unable to release dialog: %w", err)
 		}
 	}()
 

v3/pkg/application/errors.go

@@ -3,14 +3,53 @@ package application
 import (
 	"fmt"
 	"os"
+	"strings"
 )
 
-func Fatal(message string, args ...interface{}) {
+// FatalError instances are passed to the registered error handler
-	println("*********************** FATAL ***********************")
+// in case of catastrophic, unrecoverable failures that require immediate termination.
-	println("There has been a catastrophic failure in your application.")
+// FatalError wraps the original error value in an informative message.
-	println("Please report this error at https://github.com/wailsapp/wails/issues")
+// The underlying error may be retrieved through the [FatalError.Unwrap] method.
-	println("******************** Error Details ******************")
+type FatalError struct {
-	println(fmt.Sprintf(message, args...))
+	err      error
-	println("*********************** FATAL ***********************")
+	internal bool
+}
+
+// Internal returns true when the error was triggered from wails' internal code.
+func (e *FatalError) Internal() bool {
+	return e.internal
+}
+
+// Unwrap returns the original cause of the fatal error,
+// for easy inspection using the [errors.As] API.
+func (e *FatalError) Unwrap() error {
+	return e.err
+}
+
+func (e *FatalError) Error() string {
+	var buffer strings.Builder
+	buffer.WriteString("\n\n******************************** FATAL *********************************\n")
+	buffer.WriteString("*      There has been a catastrophic failure in your application.      *\n")
+	if e.internal {
+		buffer.WriteString("* Please report this error at https://github.com/wailsapp/wails/issues *\n")
+	}
+	buffer.WriteString("**************************** Error Details *****************************\n")
+	buffer.WriteString(e.err.Error())
+	buffer.WriteString("************************************************************************\n")
+	return buffer.String()
+}
+
+func Fatal(message string, args ...any) {
+	err := &FatalError{
+		err:      fmt.Errorf(message, args...),
+		internal: true,
+	}
+
+	if globalApplication != nil {
+		globalApplication.handleError(err)
+	} else {
+		fmt.Println(err)
+	}
+
 	os.Exit(1)
 }

v3/pkg/application/internal/tests/services/common.go

@@ -0,0 +1,168 @@
+package services
+
+import (
+	"context"
+	"fmt"
+	"sync/atomic"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/wailsapp/wails/v3/pkg/application"
+)
+
+type Config struct {
+	Id          int
+	T           *testing.T
+	Seq         *atomic.Int64
+	Options     application.ServiceOptions
+	StartupErr  bool
+	ShutdownErr bool
+}
+
+func Configure[T any, P interface {
+	*T
+	Configure(Config)
+}](srv P, c Config) application.Service {
+	srv.Configure(c)
+	return application.NewServiceWithOptions(srv, c.Options)
+}
+
+type Error struct {
+	Id int
+}
+
+func (e *Error) Error() string {
+	return fmt.Sprintf("service #%d mock failure", e.Id)
+}
+
+type Startupper struct {
+	Config
+	startup int64
+}
+
+func (s *Startupper) Configure(c Config) {
+	s.Config = c
+}
+
+func (s *Startupper) Id() int {
+	return s.Config.Id
+}
+
+func (s *Startupper) StartupSeq() int64 {
+	return s.startup
+}
+
+func (s *Startupper) ServiceStartup(ctx context.Context, options application.ServiceOptions) error {
+	if s.startup != 0 {
+		s.T.Errorf("Double startup for service #%d: first at seq=%d, then at seq=%d", s.Id(), s.startup, s.Seq.Load())
+		return nil
+	}
+
+	s.startup = s.Seq.Add(1)
+
+	if diff := cmp.Diff(s.Options, options); diff != "" {
+		s.T.Errorf("Options mismatch for service #%d (-want +got):\n%s", s.Id(), diff)
+	}
+
+	if s.StartupErr {
+		return &Error{Id: s.Id()}
+	} else {
+		return nil
+	}
+}
+
+type Shutdowner struct {
+	Config
+	shutdown int64
+}
+
+func (s *Shutdowner) Configure(c Config) {
+	s.Config = c
+}
+
+func (s *Shutdowner) Id() int {
+	return s.Config.Id
+}
+
+func (s *Shutdowner) ShutdownSeq() int64 {
+	return s.shutdown
+}
+
+func (s *Shutdowner) ServiceShutdown() error {
+	if s.shutdown != 0 {
+		s.T.Errorf("Double shutdown for service #%d: first at seq=%d, then at seq=%d", s.Id(), s.shutdown, s.Seq.Load())
+		return nil
+	}
+
+	s.shutdown = s.Seq.Add(1)
+
+	if s.ShutdownErr {
+		return &Error{Id: s.Id()}
+	} else {
+		return nil
+	}
+}
+
+type StartupShutdowner struct {
+	Config
+	startup  int64
+	shutdown int64
+	ctx      context.Context
+}
+
+func (s *StartupShutdowner) Configure(c Config) {
+	s.Config = c
+}
+
+func (s *StartupShutdowner) Id() int {
+	return s.Config.Id
+}
+
+func (s *StartupShutdowner) StartupSeq() int64 {
+	return s.startup
+}
+
+func (s *StartupShutdowner) ShutdownSeq() int64 {
+	return s.shutdown
+}
+
+func (s *StartupShutdowner) ServiceStartup(ctx context.Context, options application.ServiceOptions) error {
+	if s.startup != 0 {
+		s.T.Errorf("Double startup for service #%d: first at seq=%d, then at seq=%d", s.Id(), s.startup, s.Seq.Load())
+		return nil
+	}
+
+	s.startup = s.Seq.Add(1)
+	s.ctx = ctx
+
+	if diff := cmp.Diff(s.Options, options); diff != "" {
+		s.T.Errorf("Options mismatch for service #%d (-want +got):\n%s", s.Id(), diff)
+	}
+
+	if s.StartupErr {
+		return &Error{Id: s.Id()}
+	} else {
+		return nil
+	}
+}
+
+func (s *StartupShutdowner) ServiceShutdown() error {
+	if s.shutdown != 0 {
+		s.T.Errorf("Double shutdown for service #%d: first at seq=%d, then at seq=%d", s.Id(), s.shutdown, s.Seq.Load())
+		return nil
+	}
+
+	s.shutdown = s.Seq.Add(1)
+
+	select {
+	case <-s.ctx.Done():
+	default:
+		s.T.Errorf("Service #%d shut down before context cancellation", s.Id())
+	}
+
+	if s.ShutdownErr {
+		return &Error{Id: s.Id()}
+	} else {
+		return nil
+	}
+}

v3/pkg/application/internal/tests/services/shutdown/shutdown_test.go

@@ -0,0 +1,92 @@
+package shutdown
+
+import (
+	"sync"
+	"sync/atomic"
+	"testing"
+
+	"github.com/wailsapp/wails/v3/pkg/application"
+	apptest "github.com/wailsapp/wails/v3/pkg/application/internal/tests"
+	svctest "github.com/wailsapp/wails/v3/pkg/application/internal/tests/services"
+	"github.com/wailsapp/wails/v3/pkg/events"
+)
+
+func TestMain(m *testing.M) {
+	apptest.Main(m)
+}
+
+type (
+	Service1 struct{ svctest.Shutdowner }
+	Service2 struct{ svctest.Shutdowner }
+	Service3 struct{ svctest.Shutdowner }
+	Service4 struct{ svctest.Shutdowner }
+	Service5 struct{ svctest.Shutdowner }
+	Service6 struct{ svctest.Shutdowner }
+)
+
+func TestServiceShutdown(t *testing.T) {
+	var seq atomic.Int64
+
+	services := []application.Service{
+		svctest.Configure(&Service1{}, svctest.Config{Id: 0, T: t, Seq: &seq}),
+		svctest.Configure(&Service2{}, svctest.Config{Id: 1, T: t, Seq: &seq}),
+		svctest.Configure(&Service3{}, svctest.Config{Id: 2, T: t, Seq: &seq}),
+		svctest.Configure(&Service4{}, svctest.Config{Id: 3, T: t, Seq: &seq}),
+		svctest.Configure(&Service5{}, svctest.Config{Id: 4, T: t, Seq: &seq}),
+		svctest.Configure(&Service6{}, svctest.Config{Id: 5, T: t, Seq: &seq}),
+	}
+
+	app := apptest.New(t, application.Options{
+		Services: services[:3],
+	})
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		app.RegisterService(services[3])
+		wg.Done()
+	}()
+	go func() {
+		app.RegisterService(services[4])
+		wg.Done()
+	}()
+	wg.Wait()
+
+	app.RegisterService(services[5])
+
+	app.OnApplicationEvent(events.Common.ApplicationStarted, func(*application.ApplicationEvent) {
+		app.Quit()
+	})
+
+	err := apptest.Run(t, app)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if count := seq.Load(); count != int64(len(services)) {
+		t.Errorf("Wrong shutdown call count: wanted %d, got %d", len(services), count)
+	}
+
+	validate(t, services[0], 5)
+	validate(t, services[1], 4)
+	validate(t, services[2], 2, 3)
+	validate(t, services[3], 1)
+	validate(t, services[4], 1)
+	validate(t, services[5], 0)
+}
+
+func validate(t *testing.T, svc application.Service, prev ...int64) {
+	id := svc.Instance().(interface{ Id() int }).Id()
+	seq := svc.Instance().(interface{ ShutdownSeq() int64 }).ShutdownSeq()
+
+	if seq == 0 {
+		t.Errorf("Service #%d did not shut down", id)
+		return
+	}
+
+	for _, p := range prev {
+		if seq <= p {
+			t.Errorf("Wrong shutdown sequence number for service #%d: wanted >%d, got %d", id, p, seq)
+		}
+	}
+}

v3/pkg/application/internal/tests/services/shutdownerror/shutdownerror_test.go

@@ -0,0 +1,123 @@
+package shutdownerror
+
+import (
+	"errors"
+	"slices"
+	"sync"
+	"sync/atomic"
+	"testing"
+
+	"github.com/wailsapp/wails/v3/pkg/application"
+	apptest "github.com/wailsapp/wails/v3/pkg/application/internal/tests"
+	svctest "github.com/wailsapp/wails/v3/pkg/application/internal/tests/services"
+	"github.com/wailsapp/wails/v3/pkg/events"
+)
+
+func TestMain(m *testing.M) {
+	apptest.Main(m)
+}
+
+type (
+	Service1 struct{ svctest.Shutdowner }
+	Service2 struct{ svctest.Shutdowner }
+	Service3 struct{ svctest.Shutdowner }
+	Service4 struct{ svctest.Shutdowner }
+	Service5 struct{ svctest.Shutdowner }
+	Service6 struct{ svctest.Shutdowner }
+)
+
+func TestServiceShutdownError(t *testing.T) {
+	var seq atomic.Int64
+
+	services := []application.Service{
+		svctest.Configure(&Service1{}, svctest.Config{Id: 0, T: t, Seq: &seq}),
+		svctest.Configure(&Service2{}, svctest.Config{Id: 1, T: t, Seq: &seq, ShutdownErr: true}),
+		svctest.Configure(&Service3{}, svctest.Config{Id: 2, T: t, Seq: &seq}),
+		svctest.Configure(&Service4{}, svctest.Config{Id: 3, T: t, Seq: &seq}),
+		svctest.Configure(&Service5{}, svctest.Config{Id: 4, T: t, Seq: &seq, ShutdownErr: true}),
+		svctest.Configure(&Service6{}, svctest.Config{Id: 5, T: t, Seq: &seq, ShutdownErr: true}),
+	}
+
+	expectedShutdownErrors := []int{5, 4, 1}
+	var errCount atomic.Int64
+
+	var app *application.App
+	app = apptest.New(t, application.Options{
+		Services: services[:3],
+		ErrorHandler: func(err error) {
+			var mock *svctest.Error
+			if !errors.As(err, &mock) {
+				app.Logger.Error(err.Error())
+				return
+			}
+
+			i := int(errCount.Add(1) - 1)
+			if i < len(expectedShutdownErrors) && mock.Id == expectedShutdownErrors[i] {
+				return
+			}
+
+			cut := min(i, len(expectedShutdownErrors))
+			if slices.Contains(expectedShutdownErrors[:cut], mock.Id) {
+				t.Errorf("Late or duplicate shutdown error for service #%d", mock.Id)
+			} else if slices.Contains(expectedShutdownErrors[cut:], mock.Id) {
+				t.Errorf("Early shutdown error for service #%d", mock.Id)
+			} else {
+				t.Errorf("Unexpected shutdown error for service #%d", mock.Id)
+			}
+		},
+	})
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		app.RegisterService(services[3])
+		wg.Done()
+	}()
+	go func() {
+		app.RegisterService(services[4])
+		wg.Done()
+	}()
+	wg.Wait()
+
+	app.RegisterService(services[5])
+
+	app.OnApplicationEvent(events.Common.ApplicationStarted, func(*application.ApplicationEvent) {
+		app.Quit()
+	})
+
+	err := apptest.Run(t, app)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if ec := errCount.Load(); ec != int64(len(expectedShutdownErrors)) {
+		t.Errorf("Wrong shutdown error count: wanted %d, got %d", len(expectedShutdownErrors), ec)
+	}
+
+	if count := seq.Load(); count != int64(len(services)) {
+		t.Errorf("Wrong shutdown call count: wanted %d, got %d", len(services), count)
+	}
+
+	validate(t, services[0], 5)
+	validate(t, services[1], 4)
+	validate(t, services[2], 2, 3)
+	validate(t, services[3], 1)
+	validate(t, services[4], 1)
+	validate(t, services[5], 0)
+}
+
+func validate(t *testing.T, svc application.Service, prev ...int64) {
+	id := svc.Instance().(interface{ Id() int }).Id()
+	seq := svc.Instance().(interface{ ShutdownSeq() int64 }).ShutdownSeq()
+
+	if seq == 0 {
+		t.Errorf("Service #%d did not shut down", id)
+		return
+	}
+
+	for _, p := range prev {
+		if seq <= p {
+			t.Errorf("Wrong shutdown sequence number for service #%d: wanted >%d, got %d", id, p, seq)
+		}
+	}
+}

v3/pkg/application/internal/tests/services/startup/startup_test.go

@@ -0,0 +1,102 @@
+package startup
+
+import (
+	"sync"
+	"sync/atomic"
+	"testing"
+
+	"github.com/wailsapp/wails/v3/pkg/application"
+	apptest "github.com/wailsapp/wails/v3/pkg/application/internal/tests"
+	svctest "github.com/wailsapp/wails/v3/pkg/application/internal/tests/services"
+	"github.com/wailsapp/wails/v3/pkg/events"
+)
+
+func TestMain(m *testing.M) {
+	apptest.Main(m)
+}
+
+type (
+	Service1 struct{ svctest.Startupper }
+	Service2 struct{ svctest.Startupper }
+	Service3 struct{ svctest.Startupper }
+	Service4 struct{ svctest.Startupper }
+	Service5 struct{ svctest.Startupper }
+	Service6 struct{ svctest.Startupper }
+)
+
+func TestServiceStartup(t *testing.T) {
+	var seq atomic.Int64
+
+	services := []application.Service{
+		svctest.Configure(&Service1{}, svctest.Config{Id: 0, T: t, Seq: &seq}),
+		svctest.Configure(&Service2{}, svctest.Config{Id: 1, T: t, Seq: &seq, Options: application.ServiceOptions{
+			Name: "I am service 2",
+		}}),
+		svctest.Configure(&Service3{}, svctest.Config{Id: 2, T: t, Seq: &seq, Options: application.ServiceOptions{
+			Route: "/mounted/here",
+		}}),
+		svctest.Configure(&Service4{}, svctest.Config{Id: 3, T: t, Seq: &seq}),
+		svctest.Configure(&Service5{}, svctest.Config{Id: 4, Seq: &seq, Options: application.ServiceOptions{
+			Name:  "I am service 5",
+			Route: "/mounted/there",
+		}}),
+		svctest.Configure(&Service6{}, svctest.Config{Id: 5, T: t, Seq: &seq, Options: application.ServiceOptions{
+			Name:  "I am service 6",
+			Route: "/mounted/elsewhere",
+		}}),
+	}
+
+	app := apptest.New(t, application.Options{
+		Services: services[:3],
+	})
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		app.RegisterService(services[3])
+		wg.Done()
+	}()
+	go func() {
+		app.RegisterService(services[4])
+		wg.Done()
+	}()
+	wg.Wait()
+
+	app.RegisterService(services[5])
+
+	app.OnApplicationEvent(events.Common.ApplicationStarted, func(*application.ApplicationEvent) {
+		app.Quit()
+	})
+
+	err := apptest.Run(t, app)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if count := seq.Load(); count != int64(len(services)) {
+		t.Errorf("Wrong startup call count: wanted %d, got %d", len(services), count)
+	}
+
+	validate(t, services[0], 0)
+	validate(t, services[1], 1)
+	validate(t, services[2], 2)
+	validate(t, services[3], 3)
+	validate(t, services[4], 3)
+	validate(t, services[5], 4, 5)
+}
+
+func validate(t *testing.T, svc application.Service, prev ...int64) {
+	id := svc.Instance().(interface{ Id() int }).Id()
+	seq := svc.Instance().(interface{ StartupSeq() int64 }).StartupSeq()
+
+	if seq == 0 {
+		t.Errorf("Service #%d did not start up", id)
+		return
+	}
+
+	for _, p := range prev {
+		if seq <= p {
+			t.Errorf("Wrong startup sequence number for service #%d: wanted >%d, got %d", id, p, seq)
+		}
+	}
+}

v3/pkg/application/internal/tests/services/startuperror/startuperror_test.go

@@ -0,0 +1,114 @@
+package startuperror
+
+import (
+	"errors"
+	"sync"
+	"sync/atomic"
+	"testing"
+
+	"github.com/wailsapp/wails/v3/pkg/application"
+	apptest "github.com/wailsapp/wails/v3/pkg/application/internal/tests"
+	svctest "github.com/wailsapp/wails/v3/pkg/application/internal/tests/services"
+	"github.com/wailsapp/wails/v3/pkg/events"
+)
+
+func TestMain(m *testing.M) {
+	apptest.Main(m)
+}
+
+type (
+	Service1 struct{ svctest.Startupper }
+	Service2 struct{ svctest.Startupper }
+	Service3 struct{ svctest.Startupper }
+	Service4 struct{ svctest.Startupper }
+	Service5 struct{ svctest.Startupper }
+	Service6 struct{ svctest.Startupper }
+)
+
+func TestServiceStartupError(t *testing.T) {
+	var seq atomic.Int64
+
+	services := []application.Service{
+		svctest.Configure(&Service1{}, svctest.Config{Id: 0, T: t, Seq: &seq}),
+		svctest.Configure(&Service2{}, svctest.Config{Id: 1, T: t, Seq: &seq}),
+		svctest.Configure(&Service3{}, svctest.Config{Id: 2, T: t, Seq: &seq}),
+		svctest.Configure(&Service4{}, svctest.Config{Id: 3, T: t, Seq: &seq, StartupErr: true}),
+		svctest.Configure(&Service5{}, svctest.Config{Id: 4, T: t, Seq: &seq, StartupErr: true}),
+		svctest.Configure(&Service6{}, svctest.Config{Id: 5, T: t, Seq: &seq, StartupErr: true}),
+	}
+
+	app := apptest.New(t, application.Options{
+		Services: services[:3],
+	})
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		app.RegisterService(services[3])
+		wg.Done()
+	}()
+	go func() {
+		app.RegisterService(services[4])
+		wg.Done()
+	}()
+	wg.Wait()
+
+	app.RegisterService(services[5])
+
+	app.OnApplicationEvent(events.Common.ApplicationStarted, func(*application.ApplicationEvent) {
+		t.Errorf("Application started")
+		app.Quit()
+	})
+
+	var mock *svctest.Error
+
+	err := apptest.Run(t, app)
+	if err != nil {
+		if !errors.As(err, &mock) {
+			t.Fatal(err)
+		}
+	}
+
+	if mock == nil {
+		t.Fatal("Wanted startup error for service #3 or #4, got none")
+	} else if mock.Id != 3 && mock.Id != 4 {
+		t.Errorf("Wanted startup error for service #3 or #4, got #%d", mock.Id)
+	}
+
+	if count := seq.Load(); count != 4 {
+		t.Errorf("Wrong startup call count: wanted %d, got %d", 4, count)
+	}
+
+	validate(t, services[0], 0)
+	validate(t, services[1], 1)
+	validate(t, services[2], 2)
+	validate(t, services[mock.Id], 3)
+
+	notStarted := 3
+	if mock.Id == 3 {
+		notStarted = 4
+	}
+
+	if seq := services[notStarted].Instance().(interface{ StartupSeq() int64 }).StartupSeq(); seq != 0 {
+		t.Errorf("Service #%d started up unexpectedly at seq=%d", notStarted, seq)
+	}
+	if seq := services[5].Instance().(interface{ StartupSeq() int64 }).StartupSeq(); seq != 0 {
+		t.Errorf("Service #5 started up unexpectedly at seq=%d", seq)
+	}
+}
+
+func validate(t *testing.T, svc application.Service, prev ...int64) {
+	id := svc.Instance().(interface{ Id() int }).Id()
+	seq := svc.Instance().(interface{ StartupSeq() int64 }).StartupSeq()
+
+	if seq == 0 {
+		t.Errorf("Service #%d did not start up", id)
+		return
+	}
+
+	for _, p := range prev {
+		if seq <= p {
+			t.Errorf("Wrong startup sequence number for service #%d: wanted >%d, got %d", id, p, seq)
+		}
+	}
+}

v3/pkg/application/internal/tests/services/startupshutdown/startupshutdown_test.go

@@ -0,0 +1,102 @@
+package startupshutdown
+
+import (
+	"sync"
+	"sync/atomic"
+	"testing"
+
+	"github.com/wailsapp/wails/v3/pkg/application"
+	apptest "github.com/wailsapp/wails/v3/pkg/application/internal/tests"
+	svctest "github.com/wailsapp/wails/v3/pkg/application/internal/tests/services"
+	"github.com/wailsapp/wails/v3/pkg/events"
+)
+
+func TestMain(m *testing.M) {
+	apptest.Main(m)
+}
+
+type (
+	Service1 struct{ svctest.StartupShutdowner }
+	Service2 struct{ svctest.StartupShutdowner }
+	Service3 struct{ svctest.StartupShutdowner }
+	Service4 struct{ svctest.StartupShutdowner }
+	Service5 struct{ svctest.StartupShutdowner }
+	Service6 struct{ svctest.StartupShutdowner }
+)
+
+func TestServiceStartupShutdown(t *testing.T) {
+	var seq atomic.Int64
+
+	services := []application.Service{
+		svctest.Configure(&Service1{}, svctest.Config{Id: 0, T: t, Seq: &seq}),
+		svctest.Configure(&Service2{}, svctest.Config{Id: 1, T: t, Seq: &seq}),
+		svctest.Configure(&Service3{}, svctest.Config{Id: 2, T: t, Seq: &seq}),
+		svctest.Configure(&Service4{}, svctest.Config{Id: 3, T: t, Seq: &seq}),
+		svctest.Configure(&Service5{}, svctest.Config{Id: 4, T: t, Seq: &seq}),
+		svctest.Configure(&Service6{}, svctest.Config{Id: 5, T: t, Seq: &seq}),
+	}
+
+	app := apptest.New(t, application.Options{
+		Services: services[:3],
+	})
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		app.RegisterService(services[3])
+		wg.Done()
+	}()
+	go func() {
+		app.RegisterService(services[4])
+		wg.Done()
+	}()
+	wg.Wait()
+
+	app.RegisterService(services[5])
+
+	app.OnApplicationEvent(events.Common.ApplicationStarted, func(*application.ApplicationEvent) {
+		if count := seq.Load(); count != int64(len(services)) {
+			t.Errorf("Wrong startup call count: wanted %d, got %d", len(services), count)
+		}
+		seq.Store(0)
+		app.Quit()
+	})
+
+	err := apptest.Run(t, app)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if count := seq.Load(); count != int64(len(services)) {
+		t.Errorf("Wrong shutdown call count: wanted %d, got %d", len(services), count)
+	}
+
+	bound := int64(len(services)) + 1
+	validate(t, services[0], bound)
+	validate(t, services[1], bound)
+	validate(t, services[2], bound)
+	validate(t, services[3], bound)
+	validate(t, services[4], bound)
+	validate(t, services[5], bound)
+}
+
+func validate(t *testing.T, svc application.Service, bound int64) {
+	id := svc.Instance().(interface{ Id() int }).Id()
+	startup := svc.Instance().(interface{ StartupSeq() int64 }).StartupSeq()
+	shutdown := svc.Instance().(interface{ ShutdownSeq() int64 }).ShutdownSeq()
+
+	if startup == 0 && shutdown == 0 {
+		t.Errorf("Service #%d did not start nor shut down", id)
+		return
+	} else if startup == 0 {
+		t.Errorf("Service #%d started, but did not shut down", id)
+		return
+	} else if shutdown == 0 {
+		t.Errorf("Service #%d shut down, but did not start", id)
+		return
+	}
+
+	if shutdown != bound-startup {
+		t.Errorf("Wrong sequence numbers for service #%d: wanted either %d..%d or %d..%d, got %d..%d", id, startup, bound-startup, bound-shutdown, shutdown, startup, shutdown)
+	}
+}

v3/pkg/application/internal/tests/services/startupshutdownerror/startupshutdownerror_test.go

@@ -0,0 +1,140 @@
+package startupshutdownerror
+
+import (
+	"errors"
+	"slices"
+	"sync"
+	"sync/atomic"
+	"testing"
+
+	"github.com/wailsapp/wails/v3/pkg/application"
+	apptest "github.com/wailsapp/wails/v3/pkg/application/internal/tests"
+	svctest "github.com/wailsapp/wails/v3/pkg/application/internal/tests/services"
+	"github.com/wailsapp/wails/v3/pkg/events"
+)
+
+func TestMain(m *testing.M) {
+	apptest.Main(m)
+}
+
+type (
+	Service1 struct{ svctest.StartupShutdowner }
+	Service2 struct{ svctest.StartupShutdowner }
+	Service3 struct{ svctest.StartupShutdowner }
+	Service4 struct{ svctest.StartupShutdowner }
+	Service5 struct{ svctest.StartupShutdowner }
+	Service6 struct{ svctest.StartupShutdowner }
+)
+
+func TestServiceStartupShutdownError(t *testing.T) {
+	var seq atomic.Int64
+
+	services := []application.Service{
+		svctest.Configure(&Service1{}, svctest.Config{Id: 0, T: t, Seq: &seq}),
+		svctest.Configure(&Service2{}, svctest.Config{Id: 1, T: t, Seq: &seq, ShutdownErr: true}),
+		svctest.Configure(&Service3{}, svctest.Config{Id: 2, T: t, Seq: &seq}),
+		svctest.Configure(&Service4{}, svctest.Config{Id: 3, T: t, Seq: &seq, StartupErr: true, ShutdownErr: true}),
+		svctest.Configure(&Service5{}, svctest.Config{Id: 4, T: t, Seq: &seq, StartupErr: true, ShutdownErr: true}),
+		svctest.Configure(&Service6{}, svctest.Config{Id: 5, T: t, Seq: &seq, StartupErr: true, ShutdownErr: true}),
+	}
+
+	expectedShutdownErrors := []int{1}
+	var errCount atomic.Int64
+
+	var app *application.App
+	app = apptest.New(t, application.Options{
+		Services: services[:3],
+		ErrorHandler: func(err error) {
+			var mock *svctest.Error
+			if !errors.As(err, &mock) {
+				app.Logger.Error(err.Error())
+				return
+			}
+
+			i := int(errCount.Add(1) - 1)
+			if i < len(expectedShutdownErrors) && mock.Id == expectedShutdownErrors[i] {
+				return
+			}
+
+			cut := min(i, len(expectedShutdownErrors))
+			if slices.Contains(expectedShutdownErrors[:cut], mock.Id) {
+				t.Errorf("Late or duplicate shutdown error for service #%d", mock.Id)
+			} else if slices.Contains(expectedShutdownErrors[cut:], mock.Id) {
+				t.Errorf("Early shutdown error for service #%d", mock.Id)
+			} else {
+				t.Errorf("Unexpected shutdown error for service #%d", mock.Id)
+			}
+		},
+	})
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+	go func() {
+		app.RegisterService(services[3])
+		wg.Done()
+	}()
+	go func() {
+		app.RegisterService(services[4])
+		wg.Done()
+	}()
+	wg.Wait()
+
+	app.RegisterService(services[5])
+
+	app.OnApplicationEvent(events.Common.ApplicationStarted, func(*application.ApplicationEvent) {
+		t.Errorf("Application started")
+		app.Quit()
+	})
+
+	var mock *svctest.Error
+
+	err := apptest.Run(t, app)
+	if err != nil {
+		if !errors.As(err, &mock) {
+			t.Fatal(err)
+		}
+	}
+
+	if mock == nil {
+		t.Fatal("Wanted error for service #3 or #4, got none")
+	} else if mock.Id != 3 && mock.Id != 4 {
+		t.Errorf("Wanted error for service #3 or #4, got #%d", mock.Id)
+	}
+
+	if ec := errCount.Load(); ec != int64(len(expectedShutdownErrors)) {
+		t.Errorf("Wrong shutdown error count: wanted %d, got %d", len(expectedShutdownErrors), ec)
+	}
+
+	if count := seq.Load(); count != 4+3 {
+		t.Errorf("Wrong startup+shutdown call count: wanted %d+%d, got %d", 4, 3, count)
+	}
+
+	validate(t, services[0], true, true)
+	validate(t, services[1], true, true)
+	validate(t, services[2], true, true)
+	validate(t, services[3], mock.Id == 3, false)
+	validate(t, services[4], mock.Id == 4, false)
+	validate(t, services[5], false, false)
+}
+
+func validate(t *testing.T, svc application.Service, startup bool, shutdown bool) {
+	id := svc.Instance().(interface{ Id() int }).Id()
+	startupSeq := svc.Instance().(interface{ StartupSeq() int64 }).StartupSeq()
+	shutdownSeq := svc.Instance().(interface{ ShutdownSeq() int64 }).ShutdownSeq()
+
+	if startup != (startupSeq != 0) {
+		if startupSeq == 0 {
+			t.Errorf("Service #%d did not start up", id)
+		} else {
+			t.Errorf("Unexpected startup for service #%d at seq=%d", id, startupSeq)
+		}
+	}
+
+	if shutdown != (shutdownSeq != 0) {
+		if shutdownSeq == 0 {
+			t.Errorf("Service #%d did not shut down", id)
+		} else {
+			t.Errorf("Unexpected shutdown for service #%d at seq=%d", id, shutdownSeq)
+		}
+	}
+}

v3/pkg/application/internal/tests/utils.go

@@ -0,0 +1,74 @@
+package tests
+
+import (
+	"errors"
+	"os"
+	"runtime"
+	"testing"
+
+	"github.com/wailsapp/wails/v3/pkg/application"
+)
+
+var appChan chan *application.App = make(chan *application.App, 1)
+var errChan chan error = make(chan error, 1)
+var endChan chan error = make(chan error, 1)
+
+func init() { runtime.LockOSThread() }
+
+func New(t *testing.T, options application.Options) *application.App {
+	var app *application.App
+
+	app = application.Get()
+	if app != nil {
+		return app
+	}
+
+	if options.Name == "" {
+		options.Name = t.Name()
+	}
+
+	errorHandler := options.ErrorHandler
+	options.ErrorHandler = func(err error) {
+		if fatal := (*application.FatalError)(nil); errors.As(err, &fatal) {
+			endChan <- err
+			select {} // Block forever
+		} else if errorHandler != nil {
+			errorHandler(err)
+		} else {
+			app.Logger.Error(err.Error())
+		}
+	}
+
+	postShutdown := options.PostShutdown
+	options.PostShutdown = func() {
+		if postShutdown != nil {
+			postShutdown()
+		}
+		endChan <- nil
+		select {} // Block forever
+	}
+
+	return application.New(options)
+}
+
+func Run(t *testing.T, app *application.App) error {
+	appChan <- app
+	select {
+	case err := <-errChan:
+		return err
+	case fatal := <-endChan:
+		if fatal != nil {
+			t.Fatal(fatal)
+		}
+		return fatal
+	}
+}
+
+func Main(m *testing.M) {
+	go func() {
+		os.Exit(m.Run())
+	}()
+
+	errChan <- (<-appChan).Run()
+	select {} // Block forever
+}

v3/pkg/application/linux_cgo.go

@@ -465,7 +465,7 @@ func (a *linuxApp) setIcon(icon []byte) {
 	var gerror *C.GError
 	pixbuf := C.gdk_pixbuf_new_from_stream(stream, nil, &gerror)
 	if gerror != nil {
-		a.parent.error("Failed to load application icon: " + C.GoString(gerror.message))
+		a.parent.error("failed to load application icon: %s", C.GoString(gerror.message))
 		C.g_error_free(gerror)
 		return
 	}

v3/pkg/application/menuitem.go

@@ -1,8 +1,6 @@
 package application
 
 import (
-	"fmt"
-	"os"
 	"sync"
 	"sync/atomic"
 )
@@ -226,15 +224,13 @@ func NewRole(role Role) *MenuItem {
 		result = NewHelpMenuItem()
 
 	default:
-		globalApplication.error(fmt.Sprintf("No support for role: %v", role))
+		globalApplication.error("no support for role: %v", role)
-		os.Exit(1)
 	}
 
-	if result == nil {
+	if result != nil {
-		return nil
+		result.role = role
 	}
 
-	result.role = role
 	return result
 }
 
@@ -279,7 +275,7 @@ func (m *MenuItem) handleClick() {
 func (m *MenuItem) SetAccelerator(shortcut string) *MenuItem {
 	accelerator, err := parseAccelerator(shortcut)
 	if err != nil {
-		globalApplication.error("invalid accelerator. %v", err.Error())
+		globalApplication.error("invalid accelerator: %w", err)
 		return m
 	}
 	m.accelerator = accelerator

v3/pkg/application/menuitem_windows.go

@@ -3,8 +3,9 @@
 package application
 
 import (
-	"github.com/wailsapp/wails/v3/pkg/w32"
 	"unsafe"
+
+	"github.com/wailsapp/wails/v3/pkg/w32"
 )
 
 type windowsMenuItem struct {
@@ -121,7 +122,7 @@ func (m *windowsMenuItem) setBitmap(bitmap []byte) {
 	// Set the icon
 	err := w32.SetMenuIcons(m.hMenu, m.id, bitmap, nil)
 	if err != nil {
-		globalApplication.error("Unable to set bitmap on menu item: %s", err.Error())
+		globalApplication.error("unable to set bitmap on menu item: %w", err)
 		return
 	}
 	m.update()

v3/pkg/application/messageprocessor.go

@@ -3,6 +3,7 @@ package application
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"log/slog"
 	"net/http"
@@ -41,12 +42,12 @@ func NewMessageProcessor(logger *slog.Logger) *MessageProcessor {
 	}
 }
 
-func (m *MessageProcessor) httpError(rw http.ResponseWriter, message string, args ...any) {
+func (m *MessageProcessor) httpError(rw http.ResponseWriter, message string, err error) {
-	m.Error(message, args...)
+	m.Error(message, "error", err)
-	rw.WriteHeader(http.StatusBadRequest)
+	rw.WriteHeader(http.StatusUnprocessableEntity)
-	_, err := rw.Write([]byte(fmt.Sprintf(message, args...)))
+	_, err = rw.Write([]byte(err.Error()))
 	if err != nil {
-		m.Error("Unable to write error message: %s", err)
+		m.Error("Unable to write error response:", "error", err)
 	}
 }
 
@@ -61,12 +62,12 @@ func (m *MessageProcessor) getTargetWindow(r *http.Request) (Window, string) {
 	}
 	wID, err := strconv.ParseUint(windowID, 10, 64)
 	if err != nil {
-		m.Error("Window ID '%s' not parsable: %s", windowID, err)
+		m.Error("Window ID not parsable:", "id", windowID, "error", err)
 		return nil, windowID
 	}
 	targetWindow := globalApplication.getWindowForID(uint(wID))
 	if targetWindow == nil {
-		m.Error("Window ID %d not found", wID)
+		m.Error("Window ID not found:", "id", wID)
 		return nil, windowID
 	}
 	return targetWindow, windowID
@@ -75,7 +76,7 @@ func (m *MessageProcessor) getTargetWindow(r *http.Request) (Window, string) {
 func (m *MessageProcessor) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
 	object := r.URL.Query().Get("object")
 	if object == "" {
-		m.httpError(rw, "Invalid runtime call")
+		m.httpError(rw, "Invalid runtime call:", errors.New("missing object value"))
 		return
 	}
 
@@ -90,19 +91,19 @@ func (m *MessageProcessor) HandleRuntimeCallWithIDs(rw http.ResponseWriter, r *h
 	}()
 	object, err := strconv.Atoi(r.URL.Query().Get("object"))
 	if err != nil {
-		m.httpError(rw, "Error decoding object value: "+err.Error())
+		m.httpError(rw, "Invalid runtime call:", fmt.Errorf("error decoding object value: %w", err))
 		return
 	}
 	method, err := strconv.Atoi(r.URL.Query().Get("method"))
 	if err != nil {
-		m.httpError(rw, "Error decoding method value: "+err.Error())
+		m.httpError(rw, "Invalid runtime call:", fmt.Errorf("error decoding method value: %w", err))
 		return
 	}
 	params := QueryParams(r.URL.Query())
 
 	targetWindow, nameOrID := m.getTargetWindow(r)
 	if targetWindow == nil {
-		m.httpError(rw, fmt.Sprintf("Window '%s' not found", nameOrID))
+		m.httpError(rw, "Invalid runtime call:", fmt.Errorf("window '%s' not found", nameOrID))
 		return
 	}
 
@@ -130,7 +131,7 @@ func (m *MessageProcessor) HandleRuntimeCallWithIDs(rw http.ResponseWriter, r *h
 	case cancelCallRequesst:
 		m.processCallCancelMethod(method, rw, r, targetWindow, params)
 	default:
-		m.httpError(rw, "Unknown runtime call: %d", object)
+		m.httpError(rw, "Invalid runtime call:", fmt.Errorf("unknown object %d", object))
 	}
 }
 
@@ -150,13 +151,13 @@ func (m *MessageProcessor) json(rw http.ResponseWriter, data any) {
 	if data != nil {
 		jsonPayload, err = json.Marshal(data)
 		if err != nil {
-			m.Error("Unable to convert data to JSON. Please report this to the Wails team! Error: %s", err)
+			m.Error("Unable to convert data to JSON. Please report this to the Wails team!", "error", err)
 			return
 		}
 	}
 	_, err = rw.Write(jsonPayload)
 	if err != nil {
-		m.Error("Unable to write json payload. Please report this to the Wails team! Error: %s", err)
+		m.Error("Unable to write json payload. Please report this to the Wails team!", "error", err)
 		return
 	}
 	m.ok(rw)
@@ -165,7 +166,7 @@ func (m *MessageProcessor) json(rw http.ResponseWriter, data any) {
 func (m *MessageProcessor) text(rw http.ResponseWriter, data string) {
 	_, err := rw.Write([]byte(data))
 	if err != nil {
-		m.Error("Unable to write json payload. Please report this to the Wails team! Error: %s", err)
+		m.Error("Unable to write json payload. Please report this to the Wails team!", "error", err)
 		return
 	}
 	rw.Header().Set("Content-Type", "text/plain")

v3/pkg/application/messageprocessor_application.go

@@ -1,6 +1,7 @@
 package application
 
 import (
+	"fmt"
 	"net/http"
 )
 
@@ -28,9 +29,9 @@ func (m *MessageProcessor) processApplicationMethod(method int, rw http.Response
 		globalApplication.Show()
 		m.ok(rw)
 	default:
-		m.httpError(rw, "Unknown application method: %d", method)
+		m.httpError(rw, "Invalid application call:", fmt.Errorf("unknown method: %d", method))
+		return
 	}
 
-	m.Info("Runtime Call:", "method", "Application."+applicationMethodNames[method])
+	m.Info("Runtime call:", "method", "Application."+applicationMethodNames[method])
-
 }

v3/pkg/application/messageprocessor_browser.go

@@ -1,8 +1,11 @@
 package application
 
 import (
-	"github.com/pkg/browser"
+	"errors"
+	"fmt"
 	"net/http"
+
+	"github.com/pkg/browser"
 )
 
 const (
@@ -14,10 +17,9 @@ var browserMethods = map[int]string{
 }
 
 func (m *MessageProcessor) processBrowserMethod(method int, rw http.ResponseWriter, _ *http.Request, _ Window, params QueryParams) {
-
 	args, err := params.Args()
 	if err != nil {
-		m.httpError(rw, "Unable to parse arguments: %s", err.Error())
+		m.httpError(rw, "Invalid browser call:", fmt.Errorf("unable to parse arguments: %w", err))
 		return
 	}
 
@@ -25,19 +27,20 @@ func (m *MessageProcessor) processBrowserMethod(method int, rw http.ResponseWrit
 	case BrowserOpenURL:
 		url := args.String("url")
 		if url == nil {
-			m.Error("OpenURL: url is required")
+			m.httpError(rw, "Invalid browser call:", errors.New("missing argument 'url'"))
 			return
 		}
+
 		err := browser.OpenURL(*url)
 		if err != nil {
-			m.Error("OpenURL: %s", err.Error())
+			m.httpError(rw, "OpenURL failed:", err)
 			return
 		}
+
 		m.ok(rw)
-		m.Info("Runtime Call:", "method", "Browser."+browserMethods[method], "url", *url)
+		m.Info("Runtime call:", "method", "Browser."+browserMethods[method], "url", *url)
 	default:
-		m.httpError(rw, "Unknown browser method: %d", method)
+		m.httpError(rw, "Invalid browser call:", fmt.Errorf("unknown method: %d", method))
 		return
 	}
-
 }

v3/pkg/application/messageprocessor_call.go

@@ -3,6 +3,7 @@ package application
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/http"
 )
@@ -15,33 +16,46 @@ const (
 )
 
 func (m *MessageProcessor) callErrorCallback(window Window, message string, callID *string, err error) {
-	errorMsg := fmt.Sprintf(message, err)
+	m.Error(message, "id", *callID, "error", err)
-	m.Error(errorMsg)
+	if cerr := (*CallError)(nil); errors.As(err, &cerr) {
-	window.CallError(*callID, errorMsg)
+		if data, jsonErr := json.Marshal(cerr); jsonErr == nil {
+			window.CallError(*callID, string(data), true)
+			return
+		} else {
+			m.Error("Unable to convert data to JSON. Please report this to the Wails team!", "id", *callID, "error", jsonErr)
+		}
+	}
+
+	window.CallError(*callID, err.Error(), false)
 }
 
-func (m *MessageProcessor) callCallback(window Window, callID *string, result string, isJSON bool) {
+func (m *MessageProcessor) callCallback(window Window, callID *string, result string) {
 	window.CallResponse(*callID, result)
 }
 
 func (m *MessageProcessor) processCallCancelMethod(method int, rw http.ResponseWriter, r *http.Request, window Window, params QueryParams) {
 	args, err := params.Args()
 	if err != nil {
-		m.httpError(rw, "Unable to parse arguments: %s", err.Error())
+		m.httpError(rw, "Invalid binding call:", fmt.Errorf("unable to parse arguments: %w", err))
-		return
-	}
-	callID := args.String("call-id")
-	if callID == nil || *callID == "" {
-		m.Error("call-id is required")
 		return
 	}
 
-	m.l.Lock()
+	callID := args.String("call-id")
-	cancel := m.runningCalls[*callID]
+	if callID == nil || *callID == "" {
-	m.l.Unlock()
+		m.httpError(rw, "Invalid binding call:", errors.New("missing argument 'call-id'"))
+		return
+	}
+
+	var cancel func()
+	func() {
+		m.l.Lock()
+		defer m.l.Unlock()
+		cancel = m.runningCalls[*callID]
+	}()
 
 	if cancel != nil {
 		cancel()
+		m.Info("Binding call canceled:", "id", *callID)
 	}
 	m.ok(rw)
 }
@@ -49,12 +63,13 @@ func (m *MessageProcessor) processCallCancelMethod(method int, rw http.ResponseW
 func (m *MessageProcessor) processCallMethod(method int, rw http.ResponseWriter, r *http.Request, window Window, params QueryParams) {
 	args, err := params.Args()
 	if err != nil {
-		m.httpError(rw, "Unable to parse arguments: %s", err.Error())
+		m.httpError(rw, "Invalid binding call:", fmt.Errorf("unable to parse arguments: %w", err))
 		return
 	}
+
 	callID := args.String("call-id")
 	if callID == nil || *callID == "" {
-		m.Error("call-id is required")
+		m.httpError(rw, "Invalid binding call:", errors.New("missing argument 'call-id'"))
 		return
 	}
 
@@ -63,86 +78,116 @@ func (m *MessageProcessor) processCallMethod(method int, rw http.ResponseWriter,
 		var options CallOptions
 		err := params.ToStruct(&options)
 		if err != nil {
-			m.callErrorCallback(window, "Error parsing call options: %s", callID, err)
+			m.httpError(rw, "Invalid binding call:", fmt.Errorf("error parsing call options: %w", err))
-			return
-		}
-		var boundMethod *BoundMethod
-		if options.MethodName != "" {
-			boundMethod = globalApplication.bindings.Get(&options)
-			if boundMethod == nil {
-				m.callErrorCallback(window, "Error getting binding for method: %s", callID, fmt.Errorf("method '%s' not found", options.MethodName))
-				return
-			}
-		} else {
-			boundMethod = globalApplication.bindings.GetByID(options.MethodID)
-		}
-		if boundMethod == nil {
-			m.callErrorCallback(window, "Error getting binding for method: %s", callID, fmt.Errorf("method ID %d not found", options.MethodID))
 			return
 		}
 
 		ctx, cancel := context.WithCancel(context.WithoutCancel(r.Context()))
 
+		// Schedule cancel in case panics happen before starting the call.
+		cancelRequired := true
+		defer func() {
+			if cancelRequired {
+				cancel()
+			}
+		}()
+
 		ambiguousID := false
-		m.l.Lock()
+		func() {
-		if m.runningCalls[*callID] != nil {
+			m.l.Lock()
-			ambiguousID = true
+			defer m.l.Unlock()
-		} else {
+
-			m.runningCalls[*callID] = cancel
+			if m.runningCalls[*callID] != nil {
-		}
+				ambiguousID = true
-		m.l.Unlock()
+			} else {
+				m.runningCalls[*callID] = cancel
+			}
+		}()
 
 		if ambiguousID {
-			cancel()
+			m.httpError(rw, "Invalid binding call:", fmt.Errorf("ambiguous call id: %s", *callID))
-			m.callErrorCallback(window, "Error calling method: %s, a method call with the same id is already running", callID, err)
 			return
 		}
 
-		// Set the context values for the window
+		m.ok(rw) // From now on, failures are reported through the error callback.
-		if window != nil {
+
-			ctx = context.WithValue(ctx, WindowKey, window)
+		// Log call
+		var methodRef any = options.MethodName
+		if options.MethodName == "" {
+			methodRef = options.MethodID
 		}
+		m.Info("Binding call started:", "id", *callID, "method", methodRef)
 
 		go func() {
 			defer handlePanic()
 			defer func() {
-				cancel()
-
 				m.l.Lock()
+				defer m.l.Unlock()
 				delete(m.runningCalls, *callID)
-				m.l.Unlock()
 			}()
+			defer cancel()
+
+			var boundMethod *BoundMethod
+			if options.MethodName != "" {
+				boundMethod = globalApplication.bindings.Get(&options)
+				if boundMethod == nil {
+					m.callErrorCallback(window, "Binding call failed:", callID, &CallError{
+						Kind:    ReferenceError,
+						Message: fmt.Sprintf("unknown bound method name '%s'", options.MethodName),
+					})
+					return
+				}
+			} else {
+				boundMethod = globalApplication.bindings.GetByID(options.MethodID)
+				if boundMethod == nil {
+					m.callErrorCallback(window, "Binding call failed:", callID, &CallError{
+						Kind:    ReferenceError,
+						Message: fmt.Sprintf("unknown bound method id %d", options.MethodID),
+					})
+					return
+				}
+			}
+
+			// Prepare args for logging. This should never fail since json.Unmarshal succeeded before.
+			jsonArgs, _ := json.Marshal(options.Args)
+			var jsonResult []byte
+			defer m.Info("Binding call complete:", "id", *callID, "method", boundMethod, "args", string(jsonArgs), "result", string(jsonResult))
+
+			// Set the context values for the window
+			if window != nil {
+				ctx = context.WithValue(ctx, WindowKey, window)
+			}
 
 			result, err := boundMethod.Call(ctx, options.Args)
-			if err != nil {
+			if cerr := (*CallError)(nil); errors.As(err, &cerr) {
-				msg := fmt.Sprintf("Error calling method '%v'", boundMethod.Name)
+				switch cerr.Kind {
-				m.callErrorCallback(window, msg+": %s", callID, err)
+				case ReferenceError, TypeError:
+					m.callErrorCallback(window, "Binding call failed:", callID, cerr)
+				case RuntimeError:
+					m.callErrorCallback(window, "Bound method returned an error:", callID, cerr)
+				}
 				return
 			}
-			var jsonResult = []byte("{}")
+
 			if result != nil {
 				// convert result to json
 				jsonResult, err = json.Marshal(result)
 				if err != nil {
-					m.callErrorCallback(window, "Error converting result to json: %s", callID, err)
+					m.callErrorCallback(window, "Binding call failed:", callID, &CallError{
+						Kind:    TypeError,
+						Message: fmt.Sprintf("error marshaling result: %s", err),
+					})
 					return
 				}
 			}
-			m.callCallback(window, callID, string(jsonResult), true)
 
-			var jsonArgs struct {
+			m.callCallback(window, callID, string(jsonResult))
-				Args json.RawMessage `json:"args"`
-			}
-			err = params.ToStruct(&jsonArgs)
-			if err != nil {
-				m.callErrorCallback(window, "Error parsing arguments: %s", callID, err)
-				return
-			}
-			m.Info("Call Binding:", "method", boundMethod, "args", string(jsonArgs.Args), "result", result)
 		}()
-		m.ok(rw)
-	default:
-		m.httpError(rw, "Unknown call method: %d", method)
-	}
 
+		cancelRequired = false
+
+	default:
+		m.httpError(rw, "Invalid binding call:", fmt.Errorf("unknown method: %d", method))
+		return
+	}
 }

v3/pkg/application/messageprocessor_clipboard.go

@@ -1,6 +1,8 @@
 package application
 
 import (
+	"errors"
+	"fmt"
 	"net/http"
 )
 
@@ -15,30 +17,31 @@ var clipboardMethods = map[int]string{
 }
 
 func (m *MessageProcessor) processClipboardMethod(method int, rw http.ResponseWriter, _ *http.Request, _ Window, params QueryParams) {
-
 	args, err := params.Args()
 	if err != nil {
-		m.httpError(rw, "Unable to parse arguments: %s", err.Error())
+		m.httpError(rw, "Invalid clipboard call:", fmt.Errorf("unable to parse arguments: %w", err))
 		return
 	}
 
+	var text string
+
 	switch method {
 	case ClipboardSetText:
-		text := args.String("text")
+		textp := args.String("text")
-		if text == nil {
+		if textp == nil {
-			m.Error("SetText: text is required")
+			m.httpError(rw, "Invalid clipboard call:", errors.New("missing argument 'text'"))
 			return
 		}
-		globalApplication.Clipboard().SetText(*text)
+		text = *textp
+		globalApplication.Clipboard().SetText(text)
 		m.ok(rw)
-		m.Info("Runtime Call:", "method", "Clipboard."+clipboardMethods[method], "text", *text)
 	case ClipboardText:
-		text, _ := globalApplication.Clipboard().Text()
+		text, _ = globalApplication.Clipboard().Text()
 		m.text(rw, text)
-		m.Info("Runtime Call:", "method", "Clipboard."+clipboardMethods[method], "text", text)
 	default:
-		m.httpError(rw, "Unknown clipboard method: %d", method)
+		m.httpError(rw, "Invalid clipboard call:", fmt.Errorf("unknown method: %d", method))
 		return
 	}
 
+	m.Info("Runtime call:", "method", "Clipboard."+clipboardMethods[method], "text", text)
 }

v3/pkg/application/messageprocessor_contextmenu.go

@@ -1,6 +1,7 @@
 package application
 
 import (
+	"fmt"
 	"net/http"
 )
 
@@ -29,21 +30,21 @@ var contextmenuMethodNames = map[int]string{
 }
 
 func (m *MessageProcessor) processContextMenuMethod(method int, rw http.ResponseWriter, _ *http.Request, window Window, params QueryParams) {
-
 	switch method {
 	case ContextMenuOpen:
 		var data ContextMenuData
 		err := params.ToStruct(&data)
 		if err != nil {
-			m.httpError(rw, "error parsing contextmenu message: %s", err.Error())
+			m.httpError(rw, "Invalid contextmenu call:", fmt.Errorf("error parsing parameters: %w", err))
 			return
 		}
+
 		window.OpenContextMenu(&data)
+
 		m.ok(rw)
+		m.Info("Runtime call:", "method", "ContextMenu."+contextmenuMethodNames[method], "id", data.Id, "x", data.X, "y", data.Y, "data", data.Data)
 	default:
-		m.httpError(rw, "Unknown contextmenu method: %d", method)
+		m.httpError(rw, "Invalid contextmenu call:", fmt.Errorf("unknown method: %d", method))
+		return
 	}
-
-	m.Info("Runtime Call:", "method", "ContextMenu."+contextmenuMethodNames[method])
-
 }

v3/pkg/application/messageprocessor_dialog.go

@@ -2,6 +2,7 @@ package application
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/http"
 	"runtime"
@@ -26,9 +27,8 @@ var dialogMethodNames = map[int]string{
 }
 
 func (m *MessageProcessor) dialogErrorCallback(window Window, message string, dialogID *string, err error) {
-	errorMsg := fmt.Sprintf(message, err)
+	m.Error(message, "error", err)
-	m.Error(errorMsg)
+	window.DialogError(*dialogID, err.Error())
-	window.DialogError(*dialogID, errorMsg)
 }
 
 func (m *MessageProcessor) dialogCallback(window Window, dialogID *string, result string, isJSON bool) {
@@ -36,15 +36,15 @@ func (m *MessageProcessor) dialogCallback(window Window, dialogID *string, resul
 }
 
 func (m *MessageProcessor) processDialogMethod(method int, rw http.ResponseWriter, r *http.Request, window Window, params QueryParams) {
-
 	args, err := params.Args()
 	if err != nil {
-		m.httpError(rw, "Unable to parse arguments: %s", err.Error())
+		m.httpError(rw, "Invalid dialog call:", fmt.Errorf("unable to parse arguments: %w", err))
 		return
 	}
+
 	dialogID := args.String("dialog-id")
 	if dialogID == nil {
-		m.Error("dialog-id is required")
+		m.httpError(rw, "Invalid window call:", errors.New("missing argument 'dialog-id'"))
 		return
 	}
 
@@ -55,7 +55,7 @@ func (m *MessageProcessor) processDialogMethod(method int, rw http.ResponseWrite
 		var options MessageDialogOptions
 		err := params.ToStruct(&options)
 		if err != nil {
-			m.dialogErrorCallback(window, "Error parsing dialog options: %s", dialogID, err)
+			m.httpError(rw, "Invalid dialog call:", fmt.Errorf("error parsing dialog options: %w", err))
 			return
 		}
 		if len(options.Buttons) == 0 {
@@ -91,13 +91,13 @@ func (m *MessageProcessor) processDialogMethod(method int, rw http.ResponseWrite
 		dialog.AddButtons(options.Buttons)
 		dialog.Show()
 		m.ok(rw)
-		m.Info("Runtime Call:", "method", methodName, "options", options)
+		m.Info("Runtime call:", "method", methodName, "options", options)
 
 	case DialogOpenFile:
 		var options OpenFileDialogOptions
 		err := params.ToStruct(&options)
 		if err != nil {
-			m.httpError(rw, "Error parsing dialog options: %s", err.Error())
+			m.httpError(rw, "Invalid dialog call:", fmt.Errorf("error parsing dialog options: %w", err))
 			return
 		}
 		var detached = args.Bool("Detached")
@@ -111,35 +111,35 @@ func (m *MessageProcessor) processDialogMethod(method int, rw http.ResponseWrite
 			if options.AllowsMultipleSelection {
 				files, err := dialog.PromptForMultipleSelection()
 				if err != nil {
-					m.dialogErrorCallback(window, "Error getting selection: %s", dialogID, err)
+					m.dialogErrorCallback(window, "Dialog.OpenFile failed", dialogID, fmt.Errorf("error getting selection: %w", err))
 					return
 				} else {
 					result, err := json.Marshal(files)
 					if err != nil {
-						m.dialogErrorCallback(window, "Error marshalling files: %s", dialogID, err)
+						m.dialogErrorCallback(window, "Dialog.OpenFile failed", dialogID, fmt.Errorf("error marshaling files: %w", err))
 						return
 					}
 					m.dialogCallback(window, dialogID, string(result), true)
-					m.Info("Runtime Call:", "method", methodName, "result", result)
+					m.Info("Runtime call:", "method", methodName, "result", result)
 				}
 			} else {
 				file, err := dialog.PromptForSingleSelection()
 				if err != nil {
-					m.dialogErrorCallback(window, "Error getting selection: %s", dialogID, err)
+					m.dialogErrorCallback(window, "Dialog.OpenFile failed", dialogID, fmt.Errorf("error getting selection: %w", err))
 					return
 				}
 				m.dialogCallback(window, dialogID, file, false)
-				m.Info("Runtime Call:", "method", methodName, "result", file)
+				m.Info("Runtime call:", "method", methodName, "result", file)
 			}
 		}()
 		m.ok(rw)
-		m.Info("Runtime Call:", "method", methodName, "options", options)
+		m.Info("Runtime call:", "method", methodName, "options", options)
 
 	case DialogSaveFile:
 		var options SaveFileDialogOptions
 		err := params.ToStruct(&options)
 		if err != nil {
-			m.httpError(rw, "Error parsing dialog options: %s", err.Error())
+			m.httpError(rw, "Invalid dialog call:", fmt.Errorf("error parsing dialog options: %w", err))
 			return
 		}
 		var detached = args.Bool("Detached")
@@ -152,17 +152,17 @@ func (m *MessageProcessor) processDialogMethod(method int, rw http.ResponseWrite
 			defer handlePanic()
 			file, err := dialog.PromptForSingleSelection()
 			if err != nil {
-				m.dialogErrorCallback(window, "Error getting selection: %s", dialogID, err)
+				m.dialogErrorCallback(window, "Dialog.SaveFile failed", dialogID, fmt.Errorf("error getting selection: %w", err))
 				return
 			}
 			m.dialogCallback(window, dialogID, file, false)
-			m.Info("Runtime Call:", "method", methodName, "result", file)
+			m.Info("Runtime call:", "method", methodName, "result", file)
 		}()
 		m.ok(rw)
-		m.Info("Runtime Call:", "method", methodName, "options", options)
+		m.Info("Runtime call:", "method", methodName, "options", options)
 
 	default:
-		m.httpError(rw, "Unknown dialog method: %d", method)
+		m.httpError(rw, "Invalid dialog call:", fmt.Errorf("unknown method: %d", method))
+		return
 	}
-
 }

v3/pkg/application/messageprocessor_events.go

@@ -1,7 +1,10 @@
 package application
 
 import (
+	"fmt"
 	"net/http"
+
+	"github.com/pkg/errors"
 )
 
 const (
@@ -13,28 +16,26 @@ var eventsMethodNames = map[int]string{
 }
 
 func (m *MessageProcessor) processEventsMethod(method int, rw http.ResponseWriter, _ *http.Request, window Window, params QueryParams) {
-
-	var event CustomEvent
-
 	switch method {
 	case EventsEmit:
+		var event CustomEvent
 		err := params.ToStruct(&event)
 		if err != nil {
-			m.httpError(rw, "Error parsing event: %s", err.Error())
+			m.httpError(rw, "Invalid events call:", fmt.Errorf("error parsing event: %w", err))
 			return
 		}
 		if event.Name == "" {
-			m.httpError(rw, "Event name must be specified")
+			m.httpError(rw, "Invalid events call:", errors.New("missing event name"))
 			return
 		}
+
 		event.Sender = window.Name()
 		globalApplication.customEventProcessor.Emit(&event)
+
 		m.ok(rw)
+		m.Info("Runtime call:", "method", "Events."+eventsMethodNames[method], "name", event.Name, "sender", event.Sender, "data", event.Data, "cancelled", event.IsCancelled())
 	default:
-		m.httpError(rw, "Unknown event method: %d", method)
+		m.httpError(rw, "Invalid events call:", fmt.Errorf("unknown method: %d", method))
 		return
 	}
-
-	m.Info("Runtime Call:", "method", "Events."+eventsMethodNames[method], "name", event.Name, "sender", event.Sender, "data", event.Data, "cancelled", event.IsCancelled())
-
 }

v3/pkg/application/messageprocessor_params.go

@@ -141,6 +141,8 @@ func convertNumber[T int | int8 | int16 | int32 | int64 | uint | uint8 | uint16
 		result = v
 	case float64:
 		result = T(v)
+	default:
+		return nil
 	}
 	return &result
 }
@@ -154,6 +156,7 @@ func (a *Args) UInt8(s string) *uint8 {
 	}
 	return nil
 }
+
 func (a *Args) UInt(s string) *uint {
 	if a == nil {
 		return nil
@@ -169,8 +172,9 @@ func (a *Args) Float64(s string) *float64 {
 		return nil
 	}
 	if val := a.data[s]; val != nil {
-		result := val.(float64)
+		if result, ok := val.(float64); ok {
-		return &result
+			return &result
+		}
 	}
 	return nil
 }
@@ -180,8 +184,9 @@ func (a *Args) Bool(s string) *bool {
 		return nil
 	}
 	if val := a.data[s]; val != nil {
-		result := val.(bool)
+		if result, ok := val.(bool); ok {
-		return &result
+			return &result
+		}
 	}
 	return nil
 }

v3/pkg/application/messageprocessor_screens.go

@@ -1,6 +1,7 @@
 package application
 
 import (
+	"fmt"
 	"net/http"
 )
 
@@ -17,33 +18,33 @@ var screensMethodNames = map[int]string{
 }
 
 func (m *MessageProcessor) processScreensMethod(method int, rw http.ResponseWriter, _ *http.Request, _ Window, _ QueryParams) {
-
 	switch method {
 	case ScreensGetAll:
 		screens, err := globalApplication.GetScreens()
 		if err != nil {
-			m.Error("GetAll: %s", err.Error())
+			m.httpError(rw, "GetScreens failed:", err)
 			return
 		}
 		m.json(rw, screens)
 	case ScreensGetPrimary:
 		screen, err := globalApplication.GetPrimaryScreen()
 		if err != nil {
-			m.Error("GetPrimary: %s", err.Error())
+			m.httpError(rw, "GetPrimary failed:", err)
 			return
 		}
 		m.json(rw, screen)
 	case ScreensGetCurrent:
 		screen, err := globalApplication.CurrentWindow().GetScreen()
 		if err != nil {
-			m.Error("GetCurrent: %s", err.Error())
+			m.httpError(rw, "Window.GetScreen failed:", err)
 			return
 		}
 		m.json(rw, screen)
 	default:
-		m.httpError(rw, "Unknown screens method: %d", method)
+		m.httpError(rw, "Invalid screens call:", fmt.Errorf("unknown method: %d", method))
+		return
 	}
 
-	m.Info("Runtime Call:", "method", "Screens."+screensMethodNames[method])
+	m.Info("Runtime call:", "method", "Screens."+screensMethodNames[method])
 
 }

v3/pkg/application/messageprocessor_system.go

@@ -1,6 +1,7 @@
 package application
 
 import (
+	"fmt"
 	"net/http"
 )
 
@@ -15,16 +16,15 @@ var systemMethodNames = map[int]string{
 }
 
 func (m *MessageProcessor) processSystemMethod(method int, rw http.ResponseWriter, r *http.Request, window Window, params QueryParams) {
-
 	switch method {
 	case SystemIsDarkMode:
 		m.json(rw, globalApplication.IsDarkMode())
 	case Environment:
 		m.json(rw, globalApplication.Environment())
 	default:
-		m.httpError(rw, "Unknown system method: %d", method)
+		m.httpError(rw, "Invalid system call:", fmt.Errorf("unknown method: %d", method))
+		return
 	}
 
-	m.Info("Runtime Call:", "method", "System."+systemMethodNames[method])
+	m.Info("Runtime call:", "method", "System."+systemMethodNames[method])
-
 }

v3/pkg/application/messageprocessor_window.go

@@ -1,6 +1,8 @@
 package application
 
 import (
+	"errors"
+	"fmt"
 	"net/http"
 )
 
@@ -107,10 +109,9 @@ var windowMethodNames = map[int]string{
 }
 
 func (m *MessageProcessor) processWindowMethod(method int, rw http.ResponseWriter, _ *http.Request, window Window, params QueryParams) {
-
 	args, err := params.Args()
 	if err != nil {
-		m.httpError(rw, "Unable to parse arguments: %s", err.Error())
+		m.httpError(rw, "Invalid window call:", fmt.Errorf("unable to parse arguments: %w", err))
 		return
 	}
 
@@ -145,7 +146,7 @@ func (m *MessageProcessor) processWindowMethod(method int, rw http.ResponseWrite
 	case WindowGetScreen:
 		screen, err := window.GetScreen()
 		if err != nil {
-			m.httpError(rw, err.Error())
+			m.httpError(rw, "Window.GetScreen failed:", err)
 			return
 		}
 		m.json(rw, screen)
@@ -197,18 +198,20 @@ func (m *MessageProcessor) processWindowMethod(method int, rw http.ResponseWrite
 	case WindowSetPosition:
 		x := args.Int("x")
 		if x == nil {
-			m.Error("Invalid SetPosition Message: 'x' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'x'"))
+			return
 		}
 		y := args.Int("y")
 		if y == nil {
-			m.Error("Invalid SetPosition Message: 'y' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'y'"))
+			return
 		}
 		window.SetPosition(*x, *y)
 		m.ok(rw)
 	case WindowSetAlwaysOnTop:
 		alwaysOnTop := args.Bool("alwaysOnTop")
 		if alwaysOnTop == nil {
-			m.Error("Invalid SetAlwaysOnTop Message: 'alwaysOnTop' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'alwaysOnTop'"))
 			return
 		}
 		window.SetAlwaysOnTop(*alwaysOnTop)
@@ -216,22 +219,22 @@ func (m *MessageProcessor) processWindowMethod(method int, rw http.ResponseWrite
 	case WindowSetBackgroundColour:
 		r := args.UInt8("r")
 		if r == nil {
-			m.Error("Invalid SetBackgroundColour Message: 'r' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'r'"))
 			return
 		}
 		g := args.UInt8("g")
 		if g == nil {
-			m.Error("Invalid SetBackgroundColour Message: 'g' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'g'"))
 			return
 		}
 		b := args.UInt8("b")
 		if b == nil {
-			m.Error("Invalid SetBackgroundColour Message: 'b' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'b'"))
 			return
 		}
 		a := args.UInt8("a")
 		if a == nil {
-			m.Error("Invalid SetBackgroundColour Message: 'a' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'a'"))
 			return
 		}
 		window.SetBackgroundColour(RGBA{
@@ -244,7 +247,7 @@ func (m *MessageProcessor) processWindowMethod(method int, rw http.ResponseWrite
 	case WindowSetFrameless:
 		frameless := args.Bool("frameless")
 		if frameless == nil {
-			m.Error("Invalid SetFrameless Message: 'frameless' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'frameless'"))
 			return
 		}
 		window.SetFrameless(*frameless)
@@ -252,40 +255,46 @@ func (m *MessageProcessor) processWindowMethod(method int, rw http.ResponseWrite
 	case WindowSetMaxSize:
 		width := args.Int("width")
 		if width == nil {
-			m.Error("Invalid SetMaxSize Message: 'width' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'width'"))
+			return
 		}
 		height := args.Int("height")
 		if height == nil {
-			m.Error("Invalid SetMaxSize Message: 'height' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'height'"))
+			return
 		}
 		window.SetMaxSize(*width, *height)
 		m.ok(rw)
 	case WindowSetMinSize:
 		width := args.Int("width")
 		if width == nil {
-			m.Error("Invalid SetMinSize Message: 'width' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'width'"))
+			return
 		}
 		height := args.Int("height")
 		if height == nil {
-			m.Error("Invalid SetMinSize Message: 'height' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'height'"))
+			return
 		}
 		window.SetMinSize(*width, *height)
 		m.ok(rw)
 	case WindowSetRelativePosition:
 		x := args.Int("x")
 		if x == nil {
-			m.Error("Invalid SetRelativePosition Message: 'x' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'x'"))
+			return
 		}
 		y := args.Int("y")
 		if y == nil {
-			m.Error("Invalid SetRelativePosition Message: 'y' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'y'"))
+			return
 		}
 		window.SetRelativePosition(*x, *y)
 		m.ok(rw)
 	case WindowSetResizable:
 		resizable := args.Bool("resizable")
 		if resizable == nil {
-			m.Error("Invalid SetResizable Message: 'resizable' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'resizable'"))
 			return
 		}
 		window.SetResizable(*resizable)
@@ -293,18 +302,20 @@ func (m *MessageProcessor) processWindowMethod(method int, rw http.ResponseWrite
 	case WindowSetSize:
 		width := args.Int("width")
 		if width == nil {
-			m.Error("Invalid SetSize Message: 'width' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'width'"))
+			return
 		}
 		height := args.Int("height")
 		if height == nil {
-			m.Error("Invalid SetSize Message: 'height' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'height'"))
+			return
 		}
 		window.SetSize(*width, *height)
 		m.ok(rw)
 	case WindowSetTitle:
 		title := args.String("title")
 		if title == nil {
-			m.Error("Invalid SetTitle Message: 'title' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing argument 'title'"))
 			return
 		}
 		window.SetTitle(*title)
@@ -312,7 +323,7 @@ func (m *MessageProcessor) processWindowMethod(method int, rw http.ResponseWrite
 	case WindowSetZoom:
 		zoom := args.Float64("zoom")
 		if zoom == nil {
-			m.Error("Invalid SetZoom Message: 'zoom' value required")
+			m.httpError(rw, "Invalid window call:", errors.New("missing or invalid argument 'zoom'"))
 			return
 		}
 		window.SetZoom(*zoom)
@@ -360,8 +371,9 @@ func (m *MessageProcessor) processWindowMethod(method int, rw http.ResponseWrite
 		window.ZoomReset()
 		m.ok(rw)
 	default:
-		m.httpError(rw, "Unknown window method id: %d", method)
+		m.httpError(rw, "Invalid window call:", fmt.Errorf("unknown method %d", method))
+		return
 	}
 
-	m.Info("Runtime Call:", "method", "Window."+windowMethodNames[method])
+	m.Info("Runtime call:", "method", "Window."+windowMethodNames[method])
 }

v3/pkg/application/panic_handler.go

@@ -73,10 +73,8 @@ func handlePanic(options ...handlePanicOptions) bool {
 	}
 
 	// Get the error
-	var err error
+	err, ok := e.(error)
-	if errPanic, ok := e.(error); ok {
+	if !ok {
-		err = errPanic
-	} else {
 		err = fmt.Errorf("%v", e)
 	}
 
@@ -102,6 +100,5 @@ func processPanic(panicDetails *PanicDetails) {
 }
 
 func defaultPanicHandler(panicDetails *PanicDetails) {
-	errorMessage := fmt.Sprintf("panic error: %s\n%s", panicDetails.Error.Error(), panicDetails.StackTrace)
+	globalApplication.fatal("panic error: %w\n%s", panicDetails.Error, panicDetails.StackTrace)
-	globalApplication.fatal(errorMessage)
 }

v3/pkg/application/popupmenu_windows.go

@@ -1,7 +1,6 @@
 package application
 
 import (
-	"fmt"
 	"github.com/wailsapp/wails/v3/pkg/w32"
 )
 
@@ -133,12 +132,12 @@ func (p *Win32Menu) buildMenu(parentMenu w32.HMENU, inputMenu *Menu) {
 		}
 		ok := w32.AppendMenu(parentMenu, flags, uintptr(itemID), w32.MustStringToUTF16Ptr(menuText))
 		if !ok {
-			globalApplication.fatal(fmt.Sprintf("Error adding menu item: %s", menuText))
+			globalApplication.fatal("error adding menu item '%s'", menuText)
 		}
 		if item.bitmap != nil {
 			err := w32.SetMenuIcons(parentMenu, itemID, item.bitmap, nil)
 			if err != nil {
-				globalApplication.fatal(fmt.Sprintf("Error setting menu icons: %s", err.Error()))
+				globalApplication.fatal("error setting menu icons: %w", err)
 			}
 		}
 

v3/pkg/application/screen_windows.go

@@ -3,7 +3,7 @@
 package application
 
 import (
-	"fmt"
+	"errors"
 	"strconv"
 
 	"github.com/wailsapp/wails/v3/pkg/w32"
@@ -80,7 +80,7 @@ func getScreenForWindowHwnd(hwnd w32.HWND) (*Screen, error) {
 			return screen, nil
 		}
 	}
-	return nil, fmt.Errorf("screen not found for window")
+	return nil, errors.New("screen not found for window")
 }
 
 func hMonitorToScreenID(hMonitor uintptr) string {

v3/pkg/application/screenmanager.go

@@ -1,7 +1,7 @@
 package application
 
 import (
-	"fmt"
+	"errors"
 	"math"
 	"sort"
 )
@@ -363,7 +363,7 @@ func (s *Screen) physicalToDipRect(physicalRect Rect) Rect {
 // for future coordinate transformation between the physical and logical (DIP) space
 func (m *ScreenManager) LayoutScreens(screens []*Screen) error {
 	if screens == nil || len(screens) == 0 {
-		return fmt.Errorf("screens parameter is nil or empty")
+		return errors.New("screens parameter is nil or empty")
 	}
 	m.screens = screens
 
@@ -397,9 +397,9 @@ func (m *ScreenManager) calculateScreensDipCoordinates() error {
 		}
 	}
 	if m.primaryScreen == nil {
-		return fmt.Errorf("no primary screen found")
+		return errors.New("no primary screen found")
 	} else if len(remainingScreens) != len(m.screens)-1 {
-		return fmt.Errorf("invalid primary screen found")
+		return errors.New("invalid primary screen found")
 	}
 
 	// Build screens tree using the primary screen as root

v3/pkg/application/services.go

@@ -27,6 +27,16 @@ type ServiceOptions struct {
 	// it will be mounted on the internal asset server
 	// at the prefix specified by Route.
 	Route string
+
+	// MarshalError will be called if non-nil
+	// to marshal to JSON the error values returned by this service's methods.
+	//
+	// MarshalError is not allowed to fail,
+	// but it may return a nil slice to fall back
+	// to the globally configured error handler.
+	//
+	// If the returned slice is not nil, it must contain valid JSON.
+	MarshalError func(error) []byte
 }
 
 // DefaultServiceOptions specifies the default values of service options,
@@ -72,8 +82,17 @@ type ServiceName interface {
 // The context will be valid as long as the application is running,
 // and will be canceled right before shutdown.
 //
-// If the return value is non-nil, it is logged along with the service name,
+// Services are guaranteed to receive the startup notification
-// the startup process aborts and the application quits.
+// in the exact order in which they were either
+// listed in [Options.Services] or registered with [App.RegisterService],
+// with those from [Options.Services] coming first.
+//
+// If the return value is non-nil, the startup process aborts
+// and [App.Run] returns the error wrapped with [fmt.Errorf]
+// in a user-friendly message comprising the service name.
+// The original error can be retrieved either by calling the Unwrap method
+// or through the [errors.As] API.
+//
 // When that happens, service instances that have been already initialised
 // receive a shutdown notification.
 type ServiceStartup interface {
@@ -83,17 +102,33 @@ type ServiceStartup interface {
 // ServiceShutdown is an *optional* method that may be implemented by service instances.
 //
 // This method will be called during application shutdown. It can be used for cleaning up resources.
+// If a service has received a startup notification,
+// then it is guaranteed to receive a shutdown notification too,
+// except in case of unhandled panics during shutdown.
 //
-// If the return value is non-nil, it is logged along with the service name.
+// Services receive shutdown notifications in reverse registration order,
+// after all user-provided shutdown hooks have run (see [App.OnShutdown]).
+//
+// If the return value is non-nil, it is passed to the application's
+// configured error handler at [Options.ErrorHandler],
+// wrapped with [fmt.Errorf] in a user-friendly message comprising the service name.
+// The default behaviour is to log the error along with the service name.
+// The original error can be retrieved either by calling the Unwrap method
+// or through the [errors.As] API.
 type ServiceShutdown interface {
 	ServiceShutdown() error
 }
 
-func getServiceName(service any) string {
+func getServiceName(service Service) string {
-	// First check it conforms to ServiceName interface
+	if service.options.Name != "" {
-	if serviceName, ok := service.(ServiceName); ok {
+		return service.options.Name
-		return serviceName.ServiceName()
 	}
-	// Next, get the name from the type
+
-	return reflect.TypeOf(service).String()
+	// Check if the service implements the ServiceName interface
+	if s, ok := service.Instance().(ServiceName); ok {
+		return s.ServiceName()
+	}
+
+	// Finally, get the name from the type.
+	return reflect.TypeOf(service.Instance()).Elem().String()
 }

v3/pkg/application/single_instance_linux.go

@@ -3,12 +3,13 @@
 package application
 
 import (
-	"fmt"
+	"errors"
-	"github.com/godbus/dbus/v5"
 	"os"
 	"strings"
 	"sync"
 	"syscall"
+
+	"github.com/godbus/dbus/v5"
 )
 
 type dbusHandler func(string)
@@ -36,7 +37,7 @@ func newPlatformLock(manager *singleInstanceManager) (platformLock, error) {
 
 func (l *linuxLock) acquire(uniqueID string) error {
 	if uniqueID == "" {
-		return fmt.Errorf("UniqueID is required for single instance lock")
+		return errors.New("UniqueID is required for single instance lock")
 	}
 
 	id := "wails_app_" + strings.ReplaceAll(strings.ReplaceAll(uniqueID, "-", "_"), ".", "_")
@@ -56,11 +57,11 @@ func (l *linuxLock) acquire(uniqueID string) error {
 			secondInstanceBuffer <- message
 		})
 
-		err := conn.Export(f, dbus.ObjectPath(l.dbusPath), l.dbusName)
+		err = conn.Export(f, dbus.ObjectPath(l.dbusPath), l.dbusName)
-		if err != nil {
-			globalApplication.error(err.Error())
-		}
 	})
+	if err != nil {
+		return err
+	}
 
 	reply, err := conn.RequestName(l.dbusName, dbus.NameFlagDoNotQueue)
 	if err != nil {

v3/pkg/application/single_instance_windows.go

@@ -4,11 +4,11 @@ package application
 
 import (
 	"errors"
-	"fmt"
-	"github.com/wailsapp/wails/v3/pkg/w32"
-	"golang.org/x/sys/windows"
 	"syscall"
 	"unsafe"
+
+	"github.com/wailsapp/wails/v3/pkg/w32"
+	"golang.org/x/sys/windows"
 )
 
 var (
@@ -33,7 +33,7 @@ func newPlatformLock(manager *singleInstanceManager) (platformLock, error) {
 
 func (l *windowsLock) acquire(uniqueID string) error {
 	if uniqueID == "" {
-		return fmt.Errorf("UniqueID is required for single instance lock")
+		return errors.New("UniqueID is required for single instance lock")
 	}
 
 	l.uniqueID = uniqueID

v3/pkg/application/systemtray.go

@@ -1,7 +1,7 @@
 package application
 
 import (
-	"fmt"
+	"errors"
 	"runtime"
 	"sync"
 	"time"
@@ -123,7 +123,7 @@ func (s *SystemTray) Run() {
 
 func (s *SystemTray) PositionWindow(window *WebviewWindow, offset int) error {
 	if s.impl == nil {
-		return fmt.Errorf("system tray not running")
+		return errors.New("system tray not running")
 	}
 	return InvokeSyncWithError(func() error {
 		return s.impl.positionWindow(window, offset)

v3/pkg/application/systemtray_darwin.go

@@ -30,9 +30,9 @@ static void systemTrayHide(void* nsStatusItem) {
 */
 import "C"
 import (
+	"errors"
 	"unsafe"
 
-	"fmt"
 	"github.com/leaanthony/go-ansi-parser"
 )
 
@@ -125,7 +125,7 @@ func (s *macosSystemTray) getScreen() (*Screen, error) {
 		}
 		return result, nil
 	}
-	return nil, fmt.Errorf("no screen available")
+	return nil, errors.New("no screen available")
 }
 
 func (s *macosSystemTray) bounds() (*Rect, error) {

v3/pkg/application/systemtray_linux.go

@@ -9,13 +9,14 @@ package application
 import "C"
 import (
 	"fmt"
+	"os"
+
 	"github.com/godbus/dbus/v5"
 	"github.com/godbus/dbus/v5/introspect"
 	"github.com/godbus/dbus/v5/prop"
 	"github.com/wailsapp/wails/v3/internal/dbus/menu"
 	"github.com/wailsapp/wails/v3/internal/dbus/notifier"
 	"github.com/wailsapp/wails/v3/pkg/icons"
-	"os"
 )
 
 const (
@@ -178,7 +179,7 @@ func (s *linuxSystemTray) refresh() {
 	s.menuVersion++
 	if err := s.menuProps.Set("com.canonical.dbusmenu", "Version",
 		dbus.MakeVariant(s.menuVersion)); err != nil {
-		globalApplication.error("systray error: failed to update menu version: %v", err)
+		globalApplication.error("systray error: failed to update menu version: %w", err)
 		return
 	}
 	if err := menu.Emit(s.conn, &menu.Dbusmenu_LayoutUpdatedSignal{
@@ -187,7 +188,7 @@ func (s *linuxSystemTray) refresh() {
 			Revision: s.menuVersion,
 		},
 	}); err != nil {
-		globalApplication.error("systray error: failed to emit layout updated signal: %v", err)
+		globalApplication.error("systray error: failed to emit layout updated signal: %w", err)
 	}
 }
 
@@ -270,34 +271,34 @@ func (s *linuxSystemTray) bounds() (*Rect, error) {
 func (s *linuxSystemTray) run() {
 	conn, err := dbus.SessionBus()
 	if err != nil {
-		globalApplication.error("systray error: failed to connect to DBus: %v\n", err)
+		globalApplication.error("systray error: failed to connect to DBus: %w\n", err)
 		return
 	}
 	err = notifier.ExportStatusNotifierItem(conn, itemPath, s)
 	if err != nil {
-		globalApplication.error("systray error: failed to export status notifier item: %v\n", err)
+		globalApplication.error("systray error: failed to export status notifier item: %w\n", err)
 	}
 
 	err = menu.ExportDbusmenu(conn, menuPath, s)
 	if err != nil {
-		globalApplication.error("systray error: failed to export status notifier menu: %v", err)
+		globalApplication.error("systray error: failed to export status notifier menu: %w", err)
 		return
 	}
 
 	name := fmt.Sprintf("org.kde.StatusNotifierItem-%d-1", os.Getpid()) // register id 1 for this process
 	_, err = conn.RequestName(name, dbus.NameFlagDoNotQueue)
 	if err != nil {
-		globalApplication.error("systray error: failed to request name: %s\n", err)
+		globalApplication.error("systray error: failed to request name: %w", err)
 		// it's not critical error: continue
 	}
 	props, err := prop.Export(conn, itemPath, s.createPropSpec())
 	if err != nil {
-		globalApplication.error("systray error: failed to export notifier item properties to bus: %s\n", err)
+		globalApplication.error("systray error: failed to export notifier item properties to bus: %w", err)
 		return
 	}
 	menuProps, err := prop.Export(conn, menuPath, s.createMenuPropSpec())
 	if err != nil {
-		globalApplication.error("systray error: failed to export notifier menu properties to bus: %s\n", err)
+		globalApplication.error("systray error: failed to export notifier menu properties to bus: %w", err)
 		return
 	}
 
@@ -315,7 +316,7 @@ func (s *linuxSystemTray) run() {
 	}
 	err = conn.Export(introspect.NewIntrospectable(&node), itemPath, "org.freedesktop.DBus.Introspectable")
 	if err != nil {
-		globalApplication.error("systray error: failed to export node introspection: %s\n", err)
+		globalApplication.error("systray error: failed to export node introspection: %w", err)
 		return
 	}
 	menuNode := introspect.Node{
@@ -329,7 +330,7 @@ func (s *linuxSystemTray) run() {
 	err = conn.Export(introspect.NewIntrospectable(&menuNode), menuPath,
 		"org.freedesktop.DBus.Introspectable")
 	if err != nil {
-		globalApplication.error("systray error: failed to export menu node introspection: %s\n", err)
+		globalApplication.error("systray error: failed to export menu node introspection: %w", err)
 		return
 	}
 	s.setLabel(s.label)
@@ -344,7 +345,7 @@ func (s *linuxSystemTray) run() {
 			dbus.WithMatchMember("NameOwnerChanged"),
 			dbus.WithMatchArg(0, "org.kde.StatusNotifierWatcher"),
 		); err != nil {
-			globalApplication.error("systray error: failed to register signal matching: %v\n", err)
+			globalApplication.error("systray error: failed to register signal matching: %w", err)
 			return
 		}
 
@@ -388,7 +389,7 @@ func (s *linuxSystemTray) setIcon(icon []byte) {
 
 	iconPx, err := iconToPX(icon)
 	if err != nil {
-		globalApplication.error("systray error: failed to convert icon to PX: %s\n", err)
+		globalApplication.error("systray error: failed to convert icon to PX: %w", err)
 		return
 	}
 	s.props.SetMust("org.kde.StatusNotifierItem", "IconPixmap", []PX{iconPx})
@@ -402,7 +403,7 @@ func (s *linuxSystemTray) setIcon(icon []byte) {
 		Body: &notifier.StatusNotifierItem_NewIconSignalBody{},
 	})
 	if err != nil {
-		globalApplication.error("systray error: failed to emit new icon signal: %s\n", err)
+		globalApplication.error("systray error: failed to emit new icon signal: %w", err)
 		return
 	}
 }
@@ -445,7 +446,7 @@ func (s *linuxSystemTray) setLabel(label string) {
 	s.label = label
 
 	if err := s.props.Set("org.kde.StatusNotifierItem", "Title", dbus.MakeVariant(label)); err != nil {
-		globalApplication.error("systray error: failed to set Title prop: %s\n", err)
+		globalApplication.error("systray error: failed to set Title prop: %w", err)
 		return
 	}
 
@@ -457,7 +458,7 @@ func (s *linuxSystemTray) setLabel(label string) {
 		Path: itemPath,
 		Body: &notifier.StatusNotifierItem_NewTitleSignalBody{},
 	}); err != nil {
-		globalApplication.error("systray error: failed to emit new title signal: %s", err)
+		globalApplication.error("systray error: failed to emit new title signal: %w", err)
 		return
 	}
 
@@ -591,7 +592,7 @@ func (s *linuxSystemTray) register() bool {
 	obj := s.conn.Object("org.kde.StatusNotifierWatcher", "/StatusNotifierWatcher")
 	call := obj.Call("org.kde.StatusNotifierWatcher.RegisterStatusNotifierItem", 0, itemPath)
 	if call.Err != nil {
-		globalApplication.error("systray error: failed to register: %v\n", call.Err)
+		globalApplication.error("systray error: failed to register: %w", call.Err)
 		return false
 	}
 

v3/pkg/application/systemtray_windows.go

@@ -3,12 +3,13 @@
 package application
 
 import (
-	"fmt"
+	"errors"
-	"github.com/wailsapp/wails/v3/pkg/icons"
 	"syscall"
 	"time"
 	"unsafe"
 
+	"github.com/wailsapp/wails/v3/pkg/icons"
+
 	"github.com/samber/lo"
 
 	"github.com/wailsapp/wails/v3/pkg/events"
@@ -120,7 +121,7 @@ func (s *windowsSystemTray) bounds() (*Rect, error) {
 
 	monitor := w32.MonitorFromWindow(s.hwnd, w32.MONITOR_DEFAULTTONEAREST)
 	if monitor == 0 {
-		return nil, fmt.Errorf("failed to get monitor")
+		return nil, errors.New("failed to get monitor")
 	}
 
 	return &Rect{
@@ -186,7 +187,7 @@ func (s *windowsSystemTray) run() {
 	for retries := range 6 {
 		if !w32.ShellNotifyIcon(w32.NIM_ADD, &nid) {
 			if retries == 5 {
-				globalApplication.fatal("Failed to register system tray icon: %v", syscall.GetLastError())
+				globalApplication.fatal("failed to register system tray icon: %w", syscall.GetLastError())
 			}
 
 			time.Sleep(500 * time.Millisecond)

v3/pkg/application/webview_window.go

@@ -1,13 +1,13 @@
 package application
 
 import (
-	"encoding/json"
 	"errors"
 	"fmt"
 	"runtime"
 	"slices"
 	"strings"
 	"sync"
+	"text/template"
 
 	"github.com/leaanthony/u"
 
@@ -276,7 +276,7 @@ func processKeyBindingOptions(keyBindings map[string]func(window *WebviewWindow)
 		// Parse the key to an accelerator
 		acc, err := parseAccelerator(key)
 		if err != nil {
-			globalApplication.error("Invalid keybinding: %s", err.Error())
+			globalApplication.error("invalid keybinding: %w", err)
 			continue
 		}
 		result[acc.String()] = callback
@@ -291,40 +291,27 @@ func (w *WebviewWindow) addCancellationFunction(canceller func()) {
 	w.cancellers = append(w.cancellers, canceller)
 }
 
-// formatJS ensures the 'data' provided marshals to valid json or panics
+func (w *WebviewWindow) CallError(callID string, result string, isJSON bool) {
-func (w *WebviewWindow) formatJS(f string, callID string, data string) string {
-	j, err := json.Marshal(data)
-	if err != nil {
-		panic(err)
-	}
-	return fmt.Sprintf(f, callID, j)
-}
-
-func (w *WebviewWindow) CallError(callID string, result string) {
 	if w.impl != nil {
-		w.impl.execJS(w.formatJS("_wails.callErrorHandler('%s', %s);", callID, result))
+		w.impl.execJS(fmt.Sprintf("_wails.callErrorHandler('%s', '%s', %t);", callID, template.JSEscapeString(result), isJSON))
 	}
 }
 
 func (w *WebviewWindow) CallResponse(callID string, result string) {
 	if w.impl != nil {
-		w.impl.execJS(w.formatJS("_wails.callResultHandler('%s', %s, true);", callID, result))
+		w.impl.execJS(fmt.Sprintf("_wails.callResultHandler('%s', '%s', true);", callID, template.JSEscapeString(result)))
 	}
 }
 
 func (w *WebviewWindow) DialogError(dialogID string, result string) {
 	if w.impl != nil {
-		w.impl.execJS(w.formatJS("_wails.dialogErrorCallback('%s', %s);", dialogID, result))
+		w.impl.execJS(fmt.Sprintf("_wails.dialogErrorCallback('%s', '%s');", dialogID, template.JSEscapeString(result)))
 	}
 }
 
 func (w *WebviewWindow) DialogResponse(dialogID string, result string, isJSON bool) {
 	if w.impl != nil {
-		if isJSON {
+		w.impl.execJS(fmt.Sprintf("_wails.dialogResultCallback('%s', '%s', %t);", dialogID, template.JSEscapeString(result), isJSON))
-			w.impl.execJS(w.formatJS("_wails.dialogResultCallback('%s', %s, true);", dialogID, result))
-		} else {
-			w.impl.execJS(fmt.Sprintf("_wails.dialogResultCallback('%s', '%s', false);", dialogID, result))
-		}
 	}
 }
 
@@ -690,7 +677,7 @@ func (w *WebviewWindow) HandleMessage(message string) {
 			InvokeSync(func() {
 				err := w.startDrag()
 				if err != nil {
-					w.Error("Failed to start drag: %s", err)
+					w.Error("failed to start drag: %w", err)
 				}
 			})
 		}
@@ -698,12 +685,12 @@ func (w *WebviewWindow) HandleMessage(message string) {
 		if !w.IsFullscreen() {
 			sl := strings.Split(message, ":")
 			if len(sl) != 3 {
-				w.Error("Unknown message returned from dispatcher", "message", message)
+				w.Error("unknown message returned from dispatcher: %s", message)
 				return
 			}
 			err := w.startResize(sl[2])
 			if err != nil {
-				w.Error(err.Error())
+				w.Error("%w", err)
 			}
 		}
 	case message == "wails:runtime:ready":
@@ -714,7 +701,7 @@ func (w *WebviewWindow) HandleMessage(message string) {
 			w.ExecJS(js)
 		}
 	default:
-		w.Error("Unknown message sent via 'invoke' on frontend: %v", message)
+		w.Error("unknown message sent via 'invoke' on frontend: %v", message)
 	}
 }
 
@@ -1162,10 +1149,8 @@ func (w *WebviewWindow) Info(message string, args ...any) {
 }
 
 func (w *WebviewWindow) Error(message string, args ...any) {
-	var messageArgs []interface{}
+	args = append([]any{w.Name()}, args...)
-	messageArgs = append(messageArgs, args...)
+	globalApplication.error("in window '%s': "+message, args...)
-	messageArgs = append(messageArgs, "sender", w.Name())
-	globalApplication.error(message, messageArgs...)
 }
 
 func (w *WebviewWindow) HandleDragAndDropMessage(filenames []string) {
@@ -1182,7 +1167,7 @@ func (w *WebviewWindow) OpenContextMenu(data *ContextMenuData) {
 	// try application level context menu
 	menu, ok := globalApplication.getContextMenu(data.Id)
 	if !ok {
-		w.Error("No context menu found for id: %s", data.Id)
+		w.Error("no context menu found for id: %s", data.Id)
 		return
 	}
 	menu.setContextData(data)

v3/pkg/application/webview_window_darwin.go

@@ -832,7 +832,7 @@ func (w *macosWebviewWindow) handleKeyEvent(acceleratorString string) {
 	// Parse acceleratorString
 	accelerator, err := parseAccelerator(acceleratorString)
 	if err != nil {
-		globalApplication.error("unable to parse accelerator: %s", err.Error())
+		globalApplication.error("unable to parse accelerator: %w", err)
 		return
 	}
 	w.parent.processKeyBinding(accelerator.String())
@@ -1038,7 +1038,11 @@ func (w *macosWebviewWindow) setEnabled(enabled bool) {
 
 func (w *macosWebviewWindow) execJS(js string) {
 	InvokeAsync(func() {
-		if globalApplication.performingShutdown {
+		globalApplication.shutdownLock.Lock()
+		performingShutdown := globalApplication.performingShutdown
+		globalApplication.shutdownLock.Unlock()
+
+		if performingShutdown {
 			return
 		}
 		if w.nsWindow == nil {
@@ -1264,7 +1268,7 @@ func (w *macosWebviewWindow) run() {
 
 		startURL, err := assetserver.GetStartURL(options.URL)
 		if err != nil {
-			globalApplication.fatal(err.Error())
+			globalApplication.handleFatalError(err)
 		}
 
 		w.setURL(startURL)

v3/pkg/application/webview_window_linux.go

@@ -324,7 +324,7 @@ func (w *linuxWebviewWindow) run() {
 
 	startURL, err := assetserver.GetStartURL(w.parent.options.URL)
 	if err != nil {
-		globalApplication.fatal(err.Error())
+		globalApplication.handleFatalError(err)
 	}
 
 	w.setURL(startURL)
@@ -380,7 +380,7 @@ func (w *linuxWebviewWindow) handleKeyEvent(acceleratorString string) {
 	// Parse acceleratorString
 	// accelerator, err := parseAccelerator(acceleratorString)
 	// if err != nil {
-	// 	globalApplication.error("unable to parse accelerator: %s", err.Error())
+	// 	globalApplication.error("unable to parse accelerator: %w", err)
 	// 	return
 	// }
 	w.parent.processKeyBinding(acceleratorString)

v3/pkg/application/webview_window_windows.go

@@ -183,7 +183,7 @@ func (w *windowsWebviewWindow) print() error {
 
 func (w *windowsWebviewWindow) startResize(border string) error {
 	if !w32.ReleaseCapture() {
-		return fmt.Errorf("unable to release mouse capture")
+		return errors.New("unable to release mouse capture")
 	}
 	// Use PostMessage because we don't want to block the caller until resizing has been finished.
 	w32.PostMessage(w.hwnd, w32.WM_NCLBUTTONDOWN, edgeMap[border], 0)
@@ -192,7 +192,7 @@ func (w *windowsWebviewWindow) startResize(border string) error {
 
 func (w *windowsWebviewWindow) startDrag() error {
 	if !w32.ReleaseCapture() {
-		return fmt.Errorf("unable to release mouse capture")
+		return errors.New("unable to release mouse capture")
 	}
 	// Use PostMessage because we don't want to block the caller until dragging has been finished.
 	w32.PostMessage(w.hwnd, w32.WM_NCLBUTTONDOWN, w32.HTCAPTION, 0)
@@ -334,7 +334,7 @@ func (w *windowsWebviewWindow) run() {
 		nil)
 
 	if w.hwnd == 0 {
-		globalApplication.fatal("Unable to create window")
+		globalApplication.fatal("unable to create window")
 	}
 
 	// Ensure correct window size in case the scale factor of current screen is different from the initial one.
@@ -1465,7 +1465,7 @@ func (w *windowsWebviewWindow) setWindowMask(imageData []byte) {
 
 	data, err := pngToImage(imageData)
 	if err != nil {
-		globalApplication.fatal("Fatal error in callback setWindowMask: " + err.Error())
+		globalApplication.fatal("fatal error in callback setWindowMask: %w", err)
 	}
 
 	bitmap, err := w32.CreateHBITMAPFromImage(data)
@@ -1513,15 +1513,15 @@ func (w *windowsWebviewWindow) processRequest(req *edge.ICoreWebView2WebResource
 		useragent = strings.Join([]string{useragent, assetserver.WailsUserAgentValue}, " ")
 		err = reqHeaders.SetHeader(assetserver.HeaderUserAgent, useragent)
 		if err != nil {
-			globalApplication.fatal("Error setting UserAgent header: " + err.Error())
+			globalApplication.fatal("error setting UserAgent header: %w", err)
 		}
 		err = reqHeaders.SetHeader(webViewRequestHeaderWindowId, strconv.FormatUint(uint64(w.parent.id), 10))
 		if err != nil {
-			globalApplication.fatal("Error setting WindowId header: " + err.Error())
+			globalApplication.fatal("error setting WindowId header: %w", err)
 		}
 		err = reqHeaders.Release()
 		if err != nil {
-			globalApplication.fatal("Error releasing headers: " + err.Error())
+			globalApplication.fatal("error releasing headers: %w", err)
 		}
 	}
 
@@ -1534,7 +1534,7 @@ func (w *windowsWebviewWindow) processRequest(req *edge.ICoreWebView2WebResource
 	uri, _ := req.GetUri()
 	reqUri, err := url.ParseRequestURI(uri)
 	if err != nil {
-		globalApplication.error("Unable to parse request uri: uri='%s' error='%s'", uri, err)
+		globalApplication.error("unable to parse request uri: uri='%s' error='%w'", uri, err)
 		return
 	}
 
@@ -1553,7 +1553,7 @@ func (w *windowsWebviewWindow) processRequest(req *edge.ICoreWebView2WebResource
 			InvokeSync(fn)
 		})
 	if err != nil {
-		globalApplication.error("%s: NewRequest failed: %s", uri, err)
+		globalApplication.error("%s: NewRequest failed: %w", uri, err)
 		return
 	}
 
@@ -1572,7 +1572,7 @@ func (w *windowsWebviewWindow) setupChromium() {
 
 	webview2version, err := webviewloader.GetAvailableCoreWebView2BrowserVersionString(globalApplication.options.Windows.WebviewBrowserPath)
 	if err != nil {
-		globalApplication.error("Error getting WebView2 version: " + err.Error())
+		globalApplication.error("error getting WebView2 version: %w", err)
 		return
 	}
 	globalApplication.capabilities = capabilities.NewCapabilities(webview2version)
@@ -1614,14 +1614,14 @@ func (w *windowsWebviewWindow) setupChromium() {
 	if chromium.HasCapability(edge.SwipeNavigation) {
 		err := chromium.PutIsSwipeNavigationEnabled(opts.EnableSwipeGestures)
 		if err != nil {
-			globalApplication.fatal(err.Error())
+			globalApplication.handleFatalError(err)
 		}
 	}
 
 	if chromium.HasCapability(edge.AllowExternalDrop) {
 		err := chromium.AllowExternalDrag(false)
 		if err != nil {
-			globalApplication.fatal(err.Error())
+			globalApplication.handleFatalError(err)
 		}
 	}
 	if w.parent.options.EnableDragAndDrop {
@@ -1657,7 +1657,7 @@ func (w *windowsWebviewWindow) setupChromium() {
 			//if windowName == "Chrome_RenderWidgetHostHWND" {
 			err := w32.RegisterDragDrop(hwnd, w.dropTarget)
 			if err != nil && !errors.Is(err, syscall.Errno(w32.DRAGDROP_E_ALREADYREGISTERED)) {
-				globalApplication.error("Error registering drag and drop: " + err.Error())
+				globalApplication.error("error registering drag and drop: %w", err)
 			}
 			//}
 			return 1
@@ -1672,7 +1672,7 @@ func (w *windowsWebviewWindow) setupChromium() {
 				// warning
 				globalApplication.warning("unsupported capability: GeneralAutofillEnabled")
 			} else {
-				globalApplication.fatal(err.Error())
+				globalApplication.handleFatalError(err)
 			}
 		}
 	}
@@ -1683,7 +1683,7 @@ func (w *windowsWebviewWindow) setupChromium() {
 			if errors.Is(edge.UnsupportedCapabilityError, err) {
 				globalApplication.warning("unsupported capability: PasswordAutosaveEnabled")
 			} else {
-				globalApplication.fatal(err.Error())
+				globalApplication.handleFatalError(err)
 			}
 		}
 	}
@@ -1692,7 +1692,7 @@ func (w *windowsWebviewWindow) setupChromium() {
 	//if chromium.HasCapability(edge.AllowExternalDrop) {
 	//	err := chromium.AllowExternalDrag(w.parent.options.EnableDragAndDrop)
 	//	if err != nil {
-	//		globalApplication.fatal(err.Error())
+	//		globalApplication.handleFatalError(err)
 	//	}
 	//	if w.parent.options.EnableDragAndDrop {
 	//		chromium.MessageWithAdditionalObjectsCallback = w.processMessageWithAdditionalObjects
@@ -1702,14 +1702,14 @@ func (w *windowsWebviewWindow) setupChromium() {
 	chromium.Resize()
 	settings, err := chromium.GetSettings()
 	if err != nil {
-		globalApplication.fatal(err.Error())
+		globalApplication.handleFatalError(err)
 	}
 	if settings == nil {
-		globalApplication.fatal("Error getting settings")
+		globalApplication.fatal("error getting settings")
 	}
 	err = settings.PutAreDefaultContextMenusEnabled(debugMode || !w.parent.options.DefaultContextMenuDisabled)
 	if err != nil {
-		globalApplication.fatal(err.Error())
+		globalApplication.handleFatalError(err)
 	}
 
 	w.enableDevTools(settings)
@@ -1719,20 +1719,20 @@ func (w *windowsWebviewWindow) setupChromium() {
 	}
 	err = settings.PutIsZoomControlEnabled(w.parent.options.ZoomControlEnabled)
 	if err != nil {
-		globalApplication.fatal(err.Error())
+		globalApplication.handleFatalError(err)
 	}
 
 	err = settings.PutIsStatusBarEnabled(false)
 	if err != nil {
-		globalApplication.fatal(err.Error())
+		globalApplication.handleFatalError(err)
 	}
 	err = settings.PutAreBrowserAcceleratorKeysEnabled(false)
 	if err != nil {
-		globalApplication.fatal(err.Error())
+		globalApplication.handleFatalError(err)
 	}
 	err = settings.PutIsSwipeNavigationEnabled(false)
 	if err != nil {
-		globalApplication.fatal(err.Error())
+		globalApplication.handleFatalError(err)
 	}
 
 	if debugMode && w.parent.options.OpenInspectorOnStartup {
@@ -1761,7 +1761,7 @@ func (w *windowsWebviewWindow) setupChromium() {
 	} else {
 		startURL, err := assetserver.GetStartURL(w.parent.options.URL)
 		if err != nil {
-			globalApplication.fatal(err.Error())
+			globalApplication.handleFatalError(err)
 		}
 		w.webviewNavigationCompleted = false
 		chromium.Navigate(startURL)
@@ -1772,7 +1772,7 @@ func (w *windowsWebviewWindow) setupChromium() {
 func (w *windowsWebviewWindow) fullscreenChanged(sender *edge.ICoreWebView2, _ *edge.ICoreWebView2ContainsFullScreenElementChangedEventArgs) {
 	isFullscreen, err := sender.GetContainsFullScreenElement()
 	if err != nil {
-		globalApplication.fatal("Fatal error in callback fullscreenChanged: " + err.Error())
+		globalApplication.fatal("fatal error in callback fullscreenChanged: %w", err)
 	}
 	if isFullscreen {
 		w.fullscreen()
@@ -1817,11 +1817,11 @@ func (w *windowsWebviewWindow) navigationCompleted(sender *edge.ICoreWebView2, a
 	// Hack to make it visible: https://github.com/MicrosoftEdge/WebView2Feedback/issues/1077#issuecomment-825375026
 	err := w.chromium.Hide()
 	if err != nil {
-		globalApplication.fatal(err.Error())
+		globalApplication.handleFatalError(err)
 	}
 	err = w.chromium.Show()
 	if err != nil {
-		globalApplication.fatal(err.Error())
+		globalApplication.handleFatalError(err)
 	}
 	if wasFocused {
 		w.focus()
@@ -1839,7 +1839,7 @@ func (w *windowsWebviewWindow) processKeyBinding(vkey uint) bool {
 	// Get the keyboard state and convert to an accelerator
 	var keyState [256]byte
 	if !w32.GetKeyboardState(keyState[:]) {
-		globalApplication.error("Error getting keyboard state")
+		globalApplication.error("error getting keyboard state")
 		return false
 	}
 
@@ -1890,20 +1890,20 @@ func (w *windowsWebviewWindow) processMessageWithAdditionalObjects(message strin
 	if strings.HasPrefix(message, "FilesDropped") {
 		objs, err := args.GetAdditionalObjects()
 		if err != nil {
-			globalApplication.error(err.Error())
+			globalApplication.handleError(err)
 			return
 		}
 
 		defer func() {
 			err = objs.Release()
 			if err != nil {
-				globalApplication.error("Error releasing objects: " + err.Error())
+				globalApplication.error("error releasing objects: %w", err)
 			}
 		}()
 
 		count, err := objs.GetCount()
 		if err != nil {
-			globalApplication.error("cannot get count: %s", err.Error())
+			globalApplication.error("cannot get count: %w", err)
 			return
 		}
 
@@ -1911,7 +1911,7 @@ func (w *windowsWebviewWindow) processMessageWithAdditionalObjects(message strin
 		for i := uint32(0); i < count; i++ {
 			_file, err := objs.GetValueAtIndex(i)
 			if err != nil {
-				globalApplication.error("cannot get value at %d : %s", i, err.Error())
+				globalApplication.error("cannot get value at %d: %w", i, err)
 				return
 			}
 
@@ -1922,7 +1922,7 @@ func (w *windowsWebviewWindow) processMessageWithAdditionalObjects(message strin
 
 			filepath, err := file.GetPath()
 			if err != nil {
-				globalApplication.error("cannot get path for object at %d : %s", i, err.Error())
+				globalApplication.error("cannot get path for object at %d: %w", i, err)
 				return
 			}
 
@@ -1983,7 +1983,7 @@ func NewIconFromResource(instance w32.HINSTANCE, resId uint16) (w32.HICON, error
 	var err error
 	var result w32.HICON
 	if result = w32.LoadIconWithResourceID(instance, resId); result == 0 {
-		err = errors.New(fmt.Sprintf("Cannot load icon from resource with id %v", resId))
+		err = fmt.Errorf("cannot load icon from resource with id %v", resId)
 	}
 	return result, err
 }

v3/pkg/application/webview_window_windows_devtools.go

@@ -11,6 +11,6 @@ func (w *windowsWebviewWindow) openDevTools() {
 func (w *windowsWebviewWindow) enableDevTools(settings *edge.ICoreWebViewSettings) {
 	err := settings.PutAreDevToolsEnabled(true)
 	if err != nil {
-		globalApplication.fatal(err.Error())
+		globalApplication.handleFatalError(err)
 	}
 }

v3/pkg/application/webview_window_windows_production.go

@@ -9,6 +9,6 @@ func (w *windowsWebviewWindow) openDevTools() {}
 func (w *windowsWebviewWindow) enableDevTools(settings *edge.ICoreWebViewSettings) {
 	err := settings.PutAreDevToolsEnabled(false)
 	if err != nil {
-		globalApplication.fatal(err.Error())
+		globalApplication.handleFatalError(err)
 	}
 }

v3/pkg/application/window.go

@@ -5,7 +5,7 @@ import (
 )
 
 type Callback interface {
-	CallError(callID string, result string)
+	CallError(callID string, result string, isJSON bool)
 	CallResponse(callID string, result string)
 	DialogError(dialogID string, result string)
 	DialogResponse(dialogID string, result string, isJSON bool)