[desktop_webview_window] isWebviewAvailable

WebviewWindow.isWebviewAvailable() return true when the user not installed WebView2 Runtime yet

and when i run

final webView = await WebviewWindow.create();
webView.launch(url);

it will just show new window with white screen and then not responding

flutter doctor -v
[√] Flutter (Channel stable, 2.8.1, on Microsoft Windows [Version 10.0.19042.1466], locale en-ID)
• Flutter version 2.8.1 at C:\sdk\flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision 77d935af4d (6 weeks ago), 2021-12-16 08:37:33 -0800
• Engine revision 890a5fca2e
• Dart version 2.15.1

[√] Android toolchain - develop for Android devices (Android SDK version 32.0.0)
• Android SDK at C:\Users\rizal\AppData\Local\Android\sdk
• Platform android-32, build-tools 32.0.0
• Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
• Java version OpenJDK Runtime Environment (build 11.0.10+0-b96-7249189)
• All Android licenses accepted.

[√] Chrome - develop for the web
• Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[√] Visual Studio - develop for Windows (Visual Studio Community 2019 16.11.9)
• Visual Studio at C:\Program Files (x86)\Microsoft Visual Studio\2019\Community
• Visual Studio Community 2019 version 16.11.32106.194
• Windows 10 SDK version 10.0.19041.0

[√] Android Studio (version 2020.3)
• Android Studio at C:\Program Files\Android\Android Studio
• Flutter plugin can be installed from:
https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 11.0.10+0-b96-7249189)

[√] Connected device (3 available)
• Windows (desktop) • windows • windows-x64 • Microsoft Windows [Version 10.0.19042.1466]
• Chrome (web) • chrome • web-javascript • Google Chrome 97.0.4692.99
• Edge (web) • edge • web-javascript • Microsoft Edge 97.0.1072.55

• No issues found!

Start with WebviewWindow.isWebviewAvailable() and reproduce the reported behavior on Windows without the WebView2 Runtime. Trace how WebViewWindow.create() handles an unavailable runtime; done means the availability check returns false and the reported white, unresponsive window is avoided.