When i see the mobs like Pied piper or black death or any other mob it says "Opengl error 1283 (Stack overflow) and my minecraft is going crazy after that. It change textures and items and breaks everything i even see.

Rats version 3.2.13-1.12.2
Minecraft version 1.12.2
Forge version 14.23.5.2854
Optifine version 1.12.2 HD U F5

I dont support Optifine related issues for a large number of reasons but this sounds like something much bigger is at play here. I doubt this is Rats' fault