Clearing brower cache history and web push endpoint's expiration

A user has an endpoint and receives web push. But if he clears his browser cache, he won't receive web notifications anymore. So this endpoint becomes kind of "expired". However, if we try sending a push to this user, Mozilla always returned a "201 Created". In this specific case, could you return an error, e.g. "errno 103 - Expired URL endpoint", telling us that this endpoint won't receive web notifications anymore ? Thanks