Fix stream provider validation
Fix stream provider validation

streamlink/streamlink-twitch-gui,chhe/livestreamer-twitch-gui,streamlink/streamlink-twitch-gui,streamlink/streamlink-twitch-gui,bastimeyer/livestreamer-twitch-gui,chhe/livestreamer-twitch-gui,bastimeyer/livestreamer-twitch-gui,chhe/livestreamer-twitch-gui,bastimeyer/livestreamer-twitch-gui