[AdvancedPaste]Fix NullReferenceException on Dispose (#36428)

[AdvancedPaste] Fixed NullReferenceException on Dispose

src/modules/AdvancedPaste/AdvancedPaste/AdvancedPasteXAML/App.xaml.cs

@@ -263,7 +263,7 @@ namespace AdvancedPaste
                 if (disposing)
                 {
                     EtwTrace?.Dispose();
-                    window.Dispose();
+                    window?.Dispose();
                 }
 
                 disposedValue = true;

src/modules/AdvancedPaste/AdvancedPaste/Helpers/UserSettings.cs

@@ -154,8 +154,8 @@ namespace AdvancedPaste.Settings
             {
                 if (disposing)
                 {
-                    _cancellationTokenSource.Dispose();
-                    _watcher.Dispose();
+                    _cancellationTokenSource?.Dispose();
+                    _watcher?.Dispose();
                 }
 
                 _disposedValue = true;