Fixed repeatedly clicking Restore Default button causing crash (#7891)

Author: puppetsw

src/Files/Views/CustomFolderIcons.xaml.cs

@@ -10,6 +10,7 @@
 using Windows.ApplicationModel.AppService;
 using Windows.ApplicationModel.Core;
 using Windows.Foundation.Collections;
+using Windows.UI.Core;
 using Windows.UI.Xaml;
 using Windows.UI.Xaml.Controls;
 using Windows.UI.Xaml.Navigation;
@@ -111,14 +112,19 @@ await CoreApplication.MainView.DispatcherQueue.EnqueueAsync(() =>
 
         private async Task RestoreDefaultIcon()
         {
+            RestoreDefaultButton.IsEnabled = false;
+
             var setIconTask = IsShortcutItem ?
                 SetCustomFileIcon(selectedItemPath, null) :
                 SetCustomFolderIcon(selectedItemPath, null);
             if (await setIconTask)
             {
                 await CoreApplication.MainView.DispatcherQueue.EnqueueAsync(() =>
                 {
-                    appInstance?.FilesystemViewModel?.RefreshItems(null);
+                    appInstance?.FilesystemViewModel?.RefreshItems(null, async () =>
+                    {
+                        await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => RestoreDefaultButton.IsEnabled = true);
+                    });
                 });
             }
         }