enhance: skip update layout after detached from visual tree

Author: love-linger

src/Views/Repository.axaml.cs

@@ -376,7 +376,7 @@ private void OnDashboardLayoutUpdated(object sender, EventArgs e)
                 return;
 
             var grid = sender as Grid;
-            if (grid == null)
+            if (grid == null || !grid.IsAttachedToVisualTree())
                 return;
 
             var leftHeight = grid.Bounds.Height - 28.0 * 5;