fix: resolve root module null reference and itemsview scroll bug

src/Editor/Ghost.Editor/View/Controls/Docking/DockContainer.cs

@@ -152,8 +152,9 @@ public abstract class DockContainer : DockModule
             }
             else if (Root != null && Root.RootModule == this)
             {
-                Root.RootModule = null;
-                Root.NotifyLayoutEmpty();
+                var root = Root;
+                root.RootModule = null;
+                root.NotifyLayoutEmpty();
             }
         }
     }

src/Editor/Ghost.Editor/View/Controls/ProjectBrowser.xaml

@@ -147,7 +147,8 @@
                     ScrollViewer.HorizontalScrollBarVisibility="Disabled"
                     ScrollViewer.HorizontalScrollMode="Disabled"
                     SelectionChanged="PART_FilesView_SelectionChanged"
-                    SelectionMode="Single">
+                    SelectionMode="Single"
+                    SizeChanged="PART_FilesView_SizeChanged">
                     <ItemsView.ItemTemplate>
                         <DataTemplate x:DataType="model:ExplorerItem">
                             <ItemContainer>

src/Editor/Ghost.Editor/View/Controls/ProjectBrowser.xaml.cs

@@ -107,6 +107,14 @@ internal sealed partial class ProjectBrowser : UserControl
         _isUpdatingSelection = false;
     }
 
+    private void PART_FilesView_SizeChanged(object sender, SizeChangedEventArgs e)
+    {
+        if (e.NewSize.Width > 0 && e.NewSize.Height > 0)
+        {
+            PART_FilesView.UpdateLayout();
+        }
+    }
+
     private async void PART_FilesView_DoubleTapped(object sender, Microsoft.UI.Xaml.Input.DoubleTappedRoutedEventArgs e)
     {
         if (PART_FilesView.SelectedItem is ExplorerItem selectedItem)