Not sure if the latest Alpha version has fixed this one in particular as i haven't tested it [I also suspect the champions mod may be at fault according to my log though i'm going to need to test that.] Just thought i'd report this log just incase.

crash-2021-06-19_01.38.52-server.txt

EDIT: Can confirm it was the champions mod causing the crashes, disabling the mod seems to have resolved the issue.