A friend of mine had the following crash when disconnecting from a server:
crash-2020-12-21_22.28.33-client.txt

It should be noted that we use optifabric + optifine, though the mod doesn't conflict with it in its main function.

Due to the age of this issue and the rewrite that took place, I am closing this issue. If the issue returns please make a new issue.

Is it an everytime thing, or only sometimes?

Seems to happen every time.

Also what minecraft version are y'all using?

The log has that as well as all the mods. I can send you them in a zip in discord in case of you not being able to reproduce it (when disconnecting from a non-local server.)

(Don't know how I missed that tbh) At the current moment, I can't reproduce it, because I can't load into a server world without crashing. Though I'm doing it in a dev environment, so I'ma try in a normal install

Okay in a normal install, it didn't crash on server load, but it also didn't crash on disconnect. So the zip of mods you offered would be useful