Merge pull request #5704 from pdelvo/NREinSV

Fix a NullReferenceException in the syntax visualizer

src/Tools/Source/SyntaxVisualizer/SyntaxVisualizerControl/SyntaxVisualizerControl.xaml.cs

@@ -778,7 +778,7 @@ private void ConstantValueDetailsMenuItem_Click(object sender, RoutedEventArgs e
                 else
                 {
                     typeTextLabel.Visibility = Visibility.Visible;
-                    typeValueLabel.Content = value.Value.GetType().Name;
+                    typeValueLabel.Content = value.Value?.GetType().Name ?? "<null>";
                     _propertyGrid.SelectedObject = value;
                 }
             }