When Bairdotr chooses to join Jareth and you kill both of them, it seems the game does not recognise that she left an empty slot because I cannot ask another companion to join my party.
I cannot resurrect Bairdotr, so I am essentially stuck.
Don't have a save! And escaping the fight won't release Bairdotr from the party, so that's out. Did anyone else have Bairdotr turn against them and also have the same bug?
The save game editor cannot help yet, I don't think so
Someone else did have this problem (though with a save they could reload), and the bug report has been assigned to someone to fix, but I don't have an ETA on when that will be.
You can email supportdos@larian.com, with a brief description of the problem and the report.zip file generated by the D:OS support tool (for the PC version). The report will contain system and game information, as well as your saved games. To reduce the file size, you can delete all but your latest save from the zip.
I solved that without any trouble. You can simply attack Jareth from a distance before the dialog, in my case I used a crushing fist for his fall, and I normally killed him withou any trouble. I didn't have Baidotr an opportunity to talk to him.