camera prefab null reference fix

com.unity.render-pipelines.universal/CHANGELOG.md

@@ -34,6 +34,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed not using the local skybox on the camera game object when the Skybox Material property in the Lighting window was set to null.
 - Fixed an issue where, if URP was not in use, you would sometimes get errors about 2D Lights when going through the menus.
 - Fixed GC when using XR single-pass automated tests.
+- Fixed an issue that caused a null reference when deleting camera component in a prefab. [case 1244430](https://issuetracker.unity3d.com/issues/urp-argumentnullexception-error-is-thrown-on-removing-camera-component-from-camera-prefab)
 - Fixed resolution of intermediate textures when rendering to part of a render texture. [case 1261287](https://issuetracker.unity3d.com/product/unity/issues/guid/1261287/)
 
 ## [10.0.0] - 2019-06-10

com.unity.render-pipelines.universal/Editor/UniversalRenderPipelineCameraEditor.cs

@@ -940,13 +940,28 @@ public void RemoveComponent(Camera camera, IEnumerable<Component> dependencies)
                 return;
             }
 
-            Undo.SetCurrentGroupName("Remove Universal Camera");
-            var additionalCameraData = camera.GetComponent<UniversalAdditionalCameraData>();
-            if (additionalCameraData)
+            var isAssetEditing = EditorUtility.IsPersistent(camera);
+            try
             {
-                Undo.DestroyObjectImmediate(additionalCameraData);
+                if (isAssetEditing)
+                {
+                    AssetDatabase.StartAssetEditing();
+                }
+                Undo.SetCurrentGroupName("Remove Universal Camera");
+                var additionalCameraData = camera.GetComponent<UniversalAdditionalCameraData>();
+                if (additionalCameraData != null)
+                {
+                    Undo.DestroyObjectImmediate(additionalCameraData);
+                }
+                Undo.DestroyObjectImmediate(camera);
+            }
+            finally
+            {
+                if (isAssetEditing)
+                {
+                    AssetDatabase.StopAssetEditing();
+                }
             }
-            Undo.DestroyObjectImmediate(camera);
         }
     }
 }