Prevent a nullref when building new prims while others watch

OpenSim/Region/Environment/Scenes/Scene.cs

@@ -1772,8 +1772,8 @@ namespace OpenSim.Region.Environment.Scenes
                     AdaptTree(ref shape);
             }
 
-            sceneObject.SetGroup(groupID, null);
             AddNewSceneObject(sceneObject, true);
+            sceneObject.SetGroup(groupID, null);
 
             return sceneObject;
         }

OpenSim/Region/Environment/Scenes/SceneObjectGroup.cs

@@ -1699,6 +1699,8 @@ namespace OpenSim.Region.Environment.Scenes
 
         public void QueueForUpdateCheck()
         {
+            if (m_scene == null) // Need to check here as it's null during object creation
+                return;
             m_scene.m_sceneGraph.AddToUpdateList(this);
         }