I was just busy exploring in the End and approached a Mimicube and I wanted to throw the trident at the Mimicube and when the trident hit the Mimicube, the game had crashed, and I can't play on my own world anymore.

This should not happen anymore, please update your Alex's Mobs and forge, as both had internal changes to armor models

Thanks, the problem is gone, because I realized that my Forge needed to be updated.