it just crashed while im travelling in my world in single player in gamemode 3. it crashed when i switch to gamemode 1(creative mode)(after i enter command /gamemode 3 while in blocks).
crash-2018-10-21_12.32.24-server.txt

animania: 1.5.1.1 (mc 1.12.2)
edit: i was in walls(blocks) when switch to creative mode)

I'm pretty sure this is a duplicate of #93, and thus fixed in the next release