Improve code quality

Author: Jack251970

Flow.Launcher/ProgressBoxEx.xaml.cs

@@ -46,12 +46,9 @@ await Application.Current.Dispatcher.InvokeAsync(() =>
             {
                 if (!Application.Current.Dispatcher.CheckAccess())
                 {
-                    await Application.Current.Dispatcher.InvokeAsync(async () =>
+                    await Application.Current.Dispatcher.InvokeAsync(() =>
                     {
-                        if (prgBox != null)
-                        {
-                            await prgBox.CloseAsync();
-                        }
+                        prgBox?.Close();
                     });
                 }
             }
@@ -80,17 +77,6 @@ private void ReportProgress(double progress)
             }
         }
 
-        private async Task CloseAsync()
-        {
-            if (!Application.Current.Dispatcher.CheckAccess())
-            {
-                await Application.Current.Dispatcher.InvokeAsync(Close);
-                return;
-            }
-
-            Close();
-        }
-
         private void KeyEsc_OnPress(object sender, ExecutedRoutedEventArgs e)
         {
             ForceClose();