Refactor fetching Avalonia TopLevel

DiscordChatExporter.Gui/Utils/Extensions/AvaloniaExtensions.cs

@@ -8,14 +8,18 @@ internal static class AvaloniaExtensions
 {
     extension(IApplicationLifetime lifetime)
     {
-        public Window? TryGetMainWindow() =>
+        public Control? TryGetMainView() =>
-            lifetime is IClassicDesktopStyleApplicationLifetime desktopLifetime
+            lifetime switch
-                ? desktopLifetime.MainWindow
+            {
-                : null;
+                IClassicDesktopStyleApplicationLifetime desktopLifetime =>
+                    desktopLifetime.MainWindow,
 
-        public TopLevel? TryGetTopLevel() =>
+                ISingleViewApplicationLifetime singleViewLifetime => singleViewLifetime.MainView,
-            lifetime.TryGetMainWindow()
+
-            ?? (lifetime as ISingleViewApplicationLifetime)?.MainView?.Pipe(TopLevel.GetTopLevel);
+                _ => null,
+            };
+
+        public TopLevel? TryGetTopLevel() => lifetime.TryGetMainView()?.Pipe(TopLevel.GetTopLevel);
 
         public bool TryShutdown(int exitCode = 0)
         {