forgeversion: 1.12.2-14.23.5.2837
v0idssmartbackpacks: 1.0.6
mm: 1.9.5

This is a duplicate of #162, but it was closed without sufficient reason. I checked the issuetracker of v0idssmartbackpacks and there is no mention of this issue there, and the crash does call functions from both mods.

I have not checked if this still happens on the latest MM update becuse I currently can't update since the latest modular diversity crashes with the latest MM.

Modular Diversity is managed by another developer. His tudy to keep up to date.

This issue isn't on my end, it's one for the "v0idssmartbackpacks" mod. Can't fix this and won't do stuff to fix this on my end because it's not my issue.

Yeah I wasn't trying to pin blame on you, and I'm aware Modular Diversity isn't on your plate.
Just wanted to double check since the first issue didn't get a proper resolution. I'll post it on the v0id tracker instead.