General Info

• [X ] I am running a modpack
• I can reproduce this issue consistently
  • [ X] In single player
  • In multiplayer
• [ X] I have searched for this issue previously and it was either (1) not previously reported, or (2) previously fixed and I'm having the same problem.
• [ X] I am crashing and can provide my crash report(s)
• [ X] I am using the latest version of the mod

Client Info

• Minecraft Version:

• Forge Version: forge-1.12.2-14.23.5.2847-universal.jar

• Mod Version: Slab_Machines-1.0.6.jar

• Java Version: 1.8.0_181

Issue Description

When opening a furnace slab with the loaded mods in my already existing world (originally was SkyFactory 4 - that was when I created and placed the furnace slab - and when it worked perfectly fine), but I added some QoL mods), the game will instantly crash. The same issues does not occur with regular furnaces or any other GUIs (as far as I can tell - I still need to test the other slabs)
In contrast, creating a new world with all of the mods will result in an error on the part of the furnace slab that prevents it from being opened in the first place - WAILA gives an "error" in the description.

Reproduce Steps

Install Sky Factory 4, place a furnace slab, then add/update the following mods:
https://pastebin.com/chFZZR3v
I think most of these mods do not change any relevant behavior, so these are my suspects (essentially mods that change the inventory GUI and/or how items stack etc)

• IronBackpacks
• ToolBelt
• Stackie
• stacksize
• KeepingInventory
• VanillaFix
• NotEnoughItems

Additional Information

Crash Report: https://pastebin.com/zqhhL1BJ
I am going to be testing disabling/enabling certain mods to find the culprit of the conflict.