If trailer embedding is disabled, just try the next one instead of failing altogether

[Iskelderon]

If you continue to play past the end of a trailer, Jellyfin will just play another one, so the functionality is already there. 
But if embedding for a trailer on Youtube id disabled, Jellyfin will exit the playback attempt with an error message instead of just logging it and moving on to the next one.
This can lead to situations where the Trailer button becomes useless, since the Youtube video doesn't allow embedding and you just end up with an error message instead of the software just trying to give you the next available trailer instead so at least something plays.