At first my database got corrupted when mariadb was killed my systemd-oomd. I'm not sure if that's expected behaviour, but that's not what this bug report is about. After doing a whole lot of things to try to fix it, I came across this crash that said I should report it. I hope this is useful to you. I can provide more detail if neccesary.

I'd appreciate some insight in how to fix this as well. If it's not fixable, I'll try to recreate the database from an incomplete backup.