I've just spent ages figuring out why my MapView suddenly stopped loading and only showed as a black box. I finally tracked it down to a GraphicsLayer being added before the MapView was loaded. Why is it that this doesn't throw an exception? I can't see any case where someone would actually want their app to continue without any notification from the runtime in the event that this occurs. It also makes it a lot harder to diagnose what is actually going wrong. Is this something that can be improved in a future version?