fix: Fix crash when editing properties in the node editor

src/Beutl/ViewModels/NodeTree/NodeViewModel.cs

@@ -17,7 +17,7 @@
 
 namespace Beutl.ViewModels.NodeTree;
 
-public sealed class NodeViewModel : IDisposable, IJsonSerializable
+public sealed class NodeViewModel : IDisposable, IJsonSerializable, IPropertyEditorContextVisitor, IServiceProvider
 {
     private readonly CompositeDisposable _disposables = [];
     private readonly string _defaultName;
@@ -178,7 +178,7 @@ private NodeItemViewModel CreateNodeItemViewModel(IPropertyAdapter[] atmp, INode
             (_, PropertyEditorExtension ext) = PropertyEditorService.MatchProperty(atmp);
             ext?.TryCreateContextForNode(atmp, out context);
         }
-
+        context?.Accept(this);
         return CreateNodeItemViewModelCore(item, context);
     }
 
@@ -252,4 +252,18 @@ public void ReadFromJson(JsonObject json)
             }
         }
     }
+
+    public void Visit(IPropertyEditorContext context)
+    {
+    }
+
+    public object? GetService(Type serviceType)
+    {
+        if (serviceType == typeof(Node))
+        {
+            return Node;
+        }
+
+        return EditorContext.GetService(serviceType);
+    }
 }