Fixed undo registering when opening the graph

Author: alelievr

Assets/com.alelievr.NodeGraphProcessor/Editor/BaseGraphWindow.cs

@@ -142,7 +142,7 @@ void CloseWindowWhenSceneIsClosed(Scene closedScene)
 
 		public virtual void OnGraphDeleted()
 		{
-			if (graph != null)
+			if (graph != null && graphView != null)
 				rootView.Remove(graphView);
 
 			graphView = null;

Assets/com.alelievr.NodeGraphProcessor/Editor/Views/BaseNodeView.cs

@@ -941,11 +941,13 @@ public override void SetPosition(Rect newPos)
 		{
             if (initializing || !nodeTarget.isLocked)
             {
-                initializing = false;
                 base.SetPosition(newPos);
 
-                owner.RegisterCompleteObjectUndo("Moved graph node");
+				if (!initializing)
+					owner.RegisterCompleteObjectUndo("Moved graph node");
+
                 nodeTarget.position = newPos;
+                initializing = false;
             }
 		}