when you shift click while your in the microwave you will crash
here is the crash report
https://pastebin.com/e6nbWdjs

I have the same problem.

I'm running:
Forge version: 1.12.2 - 14.23.1.2555
Minecraft version: 1.12.2
Mod version: 4.1.5
Java: openjdk version "1.8.0_151"
Operating system: Xubuntu 16.04

Fixed in 0553e05