Should runtime error be showing when in release?

there should be a 'onerror' the same way there's a 'onend'. This would be the only safe way to handle errors. If there's no OnError function assigned, it could make the standar error notification. And, it could clear the OnError function, before calling it, if an error happens, in order to show the standar error handling in case an error occurs inside the 'onError' function.

I don't know if I should pot this somewhere else...