fix: wrong baseURL if open window twice (#3273)

mkdocs-website/docs/en/changelog.md

@@ -40,6 +40,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix replace line in `go.mod` to use relative paths. Fixes Windows paths with spaces - @leaanthony.
 - Fix MacOS systray click handling when no attached window by [thomas-senechal](https://github.com/thomas-senechal) in PR [#3207](https://github.com/wailsapp/wails/pull/3207)
 - Fix failing Windows build due to unknown option by [thomas-senechal](https://github.com/thomas-senechal) in PR [#3208](https://github.com/wailsapp/wails/pull/3208)
+- Fix wrong baseURL when open window twice by @5aaee9 in PR [#3273](https://github.com/wailsapp/wails/pull/3273)
 
 ### Changed
 

v3/internal/assetserver/assetserver.go

@@ -7,7 +7,6 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"net/url"
-	"path"
 	"strings"
 	"time"
 )
@@ -160,8 +159,7 @@ func GetStartURL(userURL string) (string, error) {
 				return "", fmt.Errorf("Error parsing URL: " + err.Error())
 			}
 			if parsedURL.Scheme == "" {
-				baseURL.Path = path.Join(baseURL.Path, userURL)
-				startURL = baseURL.String()
+				startURL = baseURL.ResolveReference(&url.URL{Path: userURL}).String()
 				// if the original URL had a trailing slash, add it back
 				if strings.HasSuffix(userURL, "/") && !strings.HasSuffix(startURL, "/") {
 					startURL = startURL + "/"