Ah, this looks wonderful! But is it possible then to expose `NotFoundHttpException` messages? If I allow this class, then I will also expose the `No route found for "%s %s"` message from RouterListener. If I don't allow this class, then I can't communicate extra information when *I* throw a 404 (unless I create my own sub-class).

Am I reading that correctly? Is it your thought that a 404 doesn't really need extra details?