Fix main window null when checking exitting

Flow.Launcher/App.xaml.cs

@@ -32,7 +32,7 @@ namespace Flow.Launcher
         #region Public Properties
 
         public static IPublicAPI API { get; private set; }
-        public static bool Exiting => _mainWindow.CanClose;
+        public static bool LoadingOrExiting => _mainWindow == null || _mainWindow.CanClose;
 
         #endregion
 

Flow.Launcher/SettingWindow.xaml.cs

@@ -82,7 +82,7 @@ public partial class SettingWindow
         _viewModel.PropertyChanged -= ViewModel_PropertyChanged;
 
         // If app is exiting, settings save is not needed because main window closing event will handle this
-        if (App.Exiting) return;
+        if (App.LoadingOrExiting) return;
         // Save settings when window is closed
         _settings.Save();
         App.API.SavePluginSettings();

Flow.Launcher/ViewModel/MainViewModel.cs

@@ -1729,7 +1729,7 @@ namespace Flow.Launcher.ViewModel
         public void Show()
         {
             // When application is exiting, we should not show the main window
-            if (App.Exiting) return;
+            if (App.LoadingOrExiting) return;
 
             // When application is exiting, the Application.Current will be null
             Application.Current?.Dispatcher.Invoke(() =>

Flow.Launcher/WelcomeWindow.xaml.cs

@@ -96,7 +96,7 @@ namespace Flow.Launcher
         private void Window_Closed(object sender, EventArgs e)
         {
             // If app is exiting, settings save is not needed because main window closing event will handle this
-            if (App.Exiting) return;
+            if (App.LoadingOrExiting) return;
             // Save settings when window is closed
             _settings.Save();
         }