[Upgrade] Zone Controller Pro package contains "LoadAssetAtPath is not allowed to be called from a ScriptableObject constructor"

1. What happened
In Zone Control Pro package lots of errors in the package on "LoadAssetAtPath is not allowed to be called from a ScriptableObject constructor (or instance field initializer), call it in OnEnable instead."
Package needs updating for 5.4.

2. How we can reproduce it using the example you attached

1. Import " Zone Controller Pro" package.
2. Open Cimenatic scene (UtopiaWorx -> Zone Controller Pro -> Demo Content -> Scenes).
3. Press Play.
4. In Hierarchy expand Canvas -> (e.g.) Lightning area -> Select New Zone.

Actual result:
In 5.4.0b17 (see screenshot attached):

LoadAssetAtPath is not allowed to be called from a ScriptableObject constructor (or instance field initializer), call it in OnEnable instead. Called from ScriptableObject 'ZoneMasterControllerEditor'.
See "Script Serialization" page in the Unity Manual for further details.
UnityEditor.EditorGUIUtility:Load(String)
ZoneMasterControllerEditor:.ctor()

In 5.4.0b4:

LoadAssetAtPath is not allowed to be called from a MonoBehaviour constructor, call it in Awake or Start instead. Called from script 'ZoneControllerEditor' on game object ''.
See "Script Serialization" page in the Unity Manual for further details.
UnityEditor.EditorGUIUtility:Load(String)
ZoneControllerEditor:.ctor()

In 5.3.4f1 (see screenshot attached): No errors.

Expected results: No errors in logs.