Question Initialize Prefab in Project Window

Dear community,

I have got a problem overhere with my custom prefab.
On my prefab, i have a script which changes the materials of some render child gameobjects,
when the script gets initialized or a script value got changed in the inspector.

However, the unity preview window works fine, everything in the scene too.
But when viewing the project-tab, i get these annoying purple "No data"-materials (view attachement):


So, and here is my"render script":
-

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. [ExecuteAlways]
6.  
7. public class BlockRenderer : MonoBehaviour
8. {
9.     BlockInfo tmp_blockInfo_before;
10.     public BlockInfo blockInfo;
11.     public MeshRenderer top;
12.     public MeshRenderer bottom;
13.     public MeshRenderer front;
14.     public MeshRenderer back;
15.     public MeshRenderer left;
16.     public MeshRenderer right;
17.  
18.     private void OnValidate()
19.     {
20.         Render();
21.     }
22.  
23.     void Render()
24.     {
25.  
26.  
27.         foreach (MeshRenderer renderer in new MeshRenderer[] { top, bottom, front, back, left, right })
28.         {
29.  
30.             Texture tex = null;
31.  
32.             if (blockInfo != null)
33.             {
34.  
35.                
36.  
37.                 if (renderer == top && blockInfo.top != null)
38.                 {
39.                     tex = blockInfo.top;
40.                 }
41.                 else if (renderer == bottom && blockInfo.bottom != null)
42.                 {
43.                     tex = blockInfo.bottom;
44.                 }
45.                 else if (blockInfo.main != null)
46.                 {
47.                     tex = blockInfo.main;
48.                 }
49.  
50.             }
51.             else
52.             {
53.                 tex = null;
54.             }
55.  
56.             Material mat = new Material(Shader.Find("Diffuse"));
57.             mat.SetTexture("_MainTex", tex);
58.             renderer.sharedMaterial = mat;
59.  
60.         }
61.  
62.        
63.     }
64.  
65. }
66.  

Any suggestions overthere?
For more details, please notify also

Best regards

 

Ok, for some reason, it is working now.
But you can still make suggestion when getting an idea