Alright, the bug appeared because Riot changed the content of the log file quite a bit. I just updated the plugin accordingly, should work fine now. Thx a lot for the bug report Zeentch, i don't stream myself so I won't notice if a LoL patch breaks the plugin.
Note: Unfortunately with the changes in the log file it's (at least for now) not possible to check if Twisted Treeline is being played. If you use unique scenes for each map and are playing Twisted Treeline, it will instead show the Summoners Rift scene for now. I will try to get it working as soon as possible.