b78cdc910b
When we use the server error to respond to user's failing to start a stream it is slow to return an error and unclear to the user what went wrong. This diff introduces a simple settings check before attempting to stream and catch and explain specific URL/key issues to the user. In the case of preset services we check there is a Stream Key before attempting to start a stream. In the case of "custom" we only verify there is a URL since for some services that's all that is required or the user may use user/password authentication.