SL-18811 Fix for reflection probes associated with an object not immediately being removed when the object is killed.

indra/newview/llviewerobject.cpp

@@ -520,6 +520,12 @@ void LLViewerObject::markDead()
 			LLFollowCamMgr::getInstance()->removeFollowCamParams(mID);
 		}
 
+        if (mReflectionProbe.notNull())
+        {
+            mReflectionProbe->mViewerObject = nullptr;
+            mReflectionProbe = nullptr;
+        }
+
 		sNumZombieObjects++;
 	}
 }