Fixed an issue that would sometimes occur when moving tabs between windows (#2285)

Author: gave92

Files/UserControls/SidebarControl.xaml.cs

@@ -288,7 +288,7 @@ private void NavigationViewItem_DragLeave(object sender, DragEventArgs e)
 
         private async void NavigationViewLocationItem_DragOver(object sender, DragEventArgs e)
         {
-            if (!((sender as Microsoft.UI.Xaml.Controls.NavigationViewItem).DataContext is LocationItem locationItem))
+            if (!((sender as Microsoft.UI.Xaml.Controls.NavigationViewItem)?.DataContext is LocationItem locationItem))
             {
                 return;
             }
@@ -324,7 +324,7 @@ private async void NavigationViewLocationItem_DragOver(object sender, DragEventA
 
                 deferral.Complete();
             }
-            else if ((e.DataView.Properties["sourceLocationItem"] as Microsoft.UI.Xaml.Controls.NavigationViewItem).DataContext is LocationItem sourceLocationItem)
+            else if ((e.DataView.Properties["sourceLocationItem"] as Microsoft.UI.Xaml.Controls.NavigationViewItem)?.DataContext is LocationItem sourceLocationItem)
             {
                 // else if the drag over event is called over a location item
 

Files/Views/ModernShellPage.xaml.cs

@@ -520,7 +520,7 @@ private void NavigationToolbar_EditModeEnabled(object sender, EventArgs e)
                 var mNavToolbar = NavigationToolbar as ModernNavigationToolbar;
                 mNavToolbar.ManualEntryBoxLoaded = true;
                 mNavToolbar.ClickablePathLoaded = false;
-                mNavToolbar.PathText = string.IsNullOrEmpty(FilesystemViewModel.WorkingDirectory)
+                mNavToolbar.PathText = string.IsNullOrEmpty(FilesystemViewModel?.WorkingDirectory)
                     ? AppSettings.HomePath
                     : FilesystemViewModel.WorkingDirectory;
             }