TextMeshPro Missing Reference Exception OnPrefabInstanceUpdate

Hello @Stephan_B

BUG 1

I found a bug related to method OnPrefabInstanceUpdate inside TMPro_UGUI_Private when asset was reimported and object was detroyed because of this process(unity 2019.3.0f1).

In code below the line "if (go == this.gameObject)" will return null because the "this" is null.
To fix the problem you should change it to "if (this != null && go == this.gameObject)"

Code (CSharp):

1. /// <summary>
2.         void OnPrefabInstanceUpdate(GameObject go)
3.         {
4.             if (go == this.gameObject) // this line will return null on asset reimport because this == null
5.             {
6.                 TMP_SubMeshUI[] subTextObjects = GetComponentsInChildren<TMP_SubMeshUI>();
7.                 if (subTextObjects.Length > 0)
8.                 {
9.                     for (int i = 0; i < subTextObjects.Length; i++)
10.                         m_subTextObjects[i + 1] = subTextObjects[i];
11.                 }
12.             }
13.         }

BUG 2

Another bug is related to TextMeshProUGUI line 370.

Sometimes this method was called before m_canvasRenderer != null. to fix the problem we can change m_canvasRenderer to property canvasRenderer or check
if (m_canvasRenderer == null) m_canvasRenderer = GetComponent<CanvasRenderer>();

Code (CSharp):

1. public override void Cull(Rect clipRect, bool validRect)
2.         {
3.             //Debug.Log("***** Cull (" + clipRect + ", " + validRect + ")   Cull: " + m_canvasRenderer.cull + " *****");
4.  
5.             if (validRect)
6.             {
7.                 m_canvasRenderer.cull = false; //This line, sometimes contains m_canvasRenderer == null in editor
8.                 CanvasUpdateRegistry.RegisterCanvasElementForGraphicRebuild(this);
9.                 return;
10.             }
11.  
12.             base.Cull(clipRect, validRect);
13.         }

 

I fixed the above issue a few days ago which appears to be resulting from some change in Unity 2019.3.

I'll take a closer look at #2.

Thank you for the detailed post