Merge pull request #1698 from Unity-Technologies/decal-projector-material-clearing

Fix DecalProjector material editor release (64 preview issue)

com.unity.render-pipelines.high-definition/CHANGELOG.md

 ### Fixed
 - Fixed an issue with PreIntegratedFGD texture being sometimes destroyed and not regenerated causing rendering to break
 - PostProcess input buffers are not copied anymore on PC if the viewport size matches the final render target size
+- Fixed an issue when manipulating a lot of decals, it was displaying a lot of errors in the inspector
 
 ### Added
 - Added support for RendererPriority on Renderer. This allow to control order of transparent rendering manually. HDRP have now two stage of sorting for transparent in addition to bact to front. Material have a priority then Renderer have a priority.

com.unity.render-pipelines.high-definition/HDRP/Editor/Material/Decal/DecalProjectorComponentEditor.cs

             m_DecalProjectorComponent.OnMaterialChange -= OnMaterialChange;
         }
 
+        private void OnDestroy()
+        {
+            DestroyImmediate(m_MaterialEditor);
+        }
+
         public void OnMaterialChange()
         {
             // Update material editor with the new material