Fixed parameter node returning a wrong value

Author: alelievr

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

@@ -102,6 +102,7 @@ public void Initialize(BaseGraphView owner, BaseNode node)
 			this.RefreshPorts();
 
 			RegisterCallback<GeometryChangedEvent>(OnGeometryChanged);
+			RegisterCallback<DetachFromPanelEvent>(e => ExceptionToLog.Call(Disable));
 			OnGeometryChanged(null);
 		}
 
@@ -580,6 +581,8 @@ void ComputeOrderUpdatedCallback()
 		public virtual void Enable(bool fromInspector = false) => DrawDefaultInspector(fromInspector);
 		public virtual void Enable() => DrawDefaultInspector(false);
 
+		public virtual void Disable() {}
+
 		Dictionary<string, List<(object value, VisualElement target)>> visibleConditions = new Dictionary<string, List<(object value, VisualElement target)>>();
 		Dictionary<string, VisualElement>  hideElementIfConnected = new Dictionary<string, VisualElement>();
 		Dictionary<FieldInfo, List<VisualElement>> fieldControlsMap = new Dictionary<FieldInfo, List<VisualElement>>();

Assets/com.alelievr.NodeGraphProcessor/Runtime/Elements/ParameterNode.cs

@@ -91,11 +91,14 @@ IEnumerable<PortData> GetInputPort(List<SerializableEdge> edges)
 			}
 		}
 
-
 		protected override void Process()
 		{
+#if UNITY_EDITOR // In the editor, an undo/redo can change the parameter instance in the graph, in this case the field in this class will point to the wrong parameter
+			parameter = graph.GetExposedParameterFromGUID(parameterGUID);
+#endif
+
 			if (accessor == ParameterAccessor.Get)
-				output = parameter?.value;
+				output = parameter.value;
 			else
 				graph.UpdateExposedParameter(parameter.guid, input);
 		}