I get an error when leaving a world, happens on both single and multiplayer. The mods i have installed are available in the crash report.
When i re-enter the game, it works fine, loads the screenshot, but when leaving it crashes. I tried your 1.0 and current github 1.1.1beta.1 and it happens on both of them.

crash-2021-02-04_21.45.02-client.txt
I do not know if this file is helpful for you, so you can ask me any question if you need.

Duplicate of #15

I should have a hot-fix ready by tomorrow night