Can´t load a canvas file after exiting Play mode

[pmhpereira]

When loading a canvas file after exiting Play mode, nothing appears in the Node Editor and a error is thrown.
It also becomes impossible to add new nodes to the canvas. The solution is to start and stop the Play mode.

Steps to reproduce:

1. Start Play mode in Unity
2. Press New Canvas in the Node Editor
3. Exit Playmode
4. Load Canvas file

MissingReferenceException: The object of type 'Texture2D' has been destroyed but you are still trying to access it. Your script should either check if it is null or you should not destroy the object. NodeEditorFramework.NodeKnob.GetGUIKnob () (at Assets/Plugins/Node_Editor/Framework/NodeKnob.cs:143)

[Seneral]

To fix that, add these lines somewhere in NodeEditor.checkInit inside the if block:

#if UNITY_EDITOR
                UnityEditor.EditorApplication.playmodeStateChanged += () => { initiated = false; InitiationError = false; };
#endif

That simply makes sure the NodeEditor is re-inited after entering and editing playmode:)