To Reproduce
Steps to reproduce the crash:

1. Open a game with Flans mod (Newest version)
2. Place out a gun modification table, and get yourself a gun (AK-47 for my crash)
3. Shift Click it while the Gun Modification table is open.
4. Game Crashes.

Versions (please complete the following information)

• Forge: 1.12.2-14.23.5.2854
• Flan's Mod:

Crash Log
https://gist.github.com/spiderking23/f9e399caf9cd21a8d67c54e4ac0c90ee

Additional context
Minecraft AVP mod is also downloaded and installed, but none of its assets were present.

Hi, this is fixed in more recent versions of the mod.
Please use the files available here: https://github.com/FlansMods/FlansMod/releases/