Fails more gracefully if audio download fails

commands.go

@@ -45,7 +45,8 @@ func parseCommand(user *gumble.User, username, command string) {
 						if err := dj.currentSong.Download(); err == nil {
 							dj.currentSong.Play()
 						} else {
-							panic(err)
+							user.Send(AUDIO_FAIL_MSG)
+							dj.currentSong.Delete()
 						}
 					}
 				} else {

strings.go

@@ -38,6 +38,9 @@ const ADMIN_SONG_SKIP_MSG = "An admin has decided to skip the current song."
 // Message shown to user when the kill command errors.
 const KILL_ERROR_MSG = "An error occurred while attempting to kill the bot."
 
+// Message shown to users when the audio for a video could not be downloaded.
+const AUDIO_FAIL_MSG = "The audio download for this video failed. YouTube has likely not generated the audio files for this video yet."
+
 // Message shown to a channel when a new song starts playing.
 const NOW_PLAYING_HTML = `
 	<table>