azubutv: set video_player to None if stream is offline
azubutv: set video_player to None if stream is offline

This prevents an error with traceback and instead just prints "No
streams found" like it should if the stream in question is not live.

wlerin/streamlink,gravyboat/streamlink,melmorabity/streamlink,mmetak/streamlink,ethanhlc/streamlink,ethanhlc/streamlink,javiercantero/streamlink,back-to/streamlink,fishscene/streamlink,streamlink/streamlink,back-to/streamlink,sbstp/streamlink,bastimeyer/streamlink,gravyboat/streamlink,sbstp/streamlink,wlerin/streamlink,beardypig/streamlink,mmetak/streamlink,chhe/streamlink,bastimeyer/streamlink,streamlink/streamlink,melmorabity/streamlink,chhe/streamlink,fishscene/streamlink,javiercantero/streamlink,beardypig/streamlink