Can't assign an image to script in animator

I've written a scrip which disables an image when an animation ends, but i can't assign the image to animator

Code (CSharp):

1. using UnityEngine;
2. using UnityEngine.UI;
3.  
4. public class afterFade : StateMachineBehaviour
5. {
6.     public Image image;
7.     override public void OnStateExit(UnityEngine.Animator animator, UnityEngine.AnimatorStateInfo animatorStateInfo, int layerIndex)
8.     {
9.         image.gameObject.SetActive(false);
10.     }
11. }

 

I confirmed this behavior with a quick test, and now I realize why. Read here:

https://forum.unity.com/threads/cant-put-public-instance-in-statemachinebehaviour.544202/

You are dragging a scene-based object into that field, and that field is stored in the actual animator asset on disk. You can't have a disk asset referring to something as transient as a scene object, in the same way you can't drag references to an in-scene prefab into a not-in-scene asset's property field.