Yep, the database is corrupt. I recommend to first make a backup of ~/.local/share/akonadi/. If you can resync everything fairly easily then delete ~/.local/share/akonadi/db* to force a recreation of the database. Otherwise you could try some of the https://mariadb.com/kb/en/innodb-recovery-modes/ to create a (hopefully complete enough) database dump and restore it after database recreation.