EDIT: SCREEN ANIMATIONS HAVE TO BE OFF TO REPRODUCE THIS ISSUE

I was in a survival world with my friend ready to fight the ender dragon and I was arranging my inventory and when he activated the portal my game crashed. So I hopped into my creative world to test, and sure enough having your inventory open while going into an end portal will crash the game. Every time.

How to reproduce

-Go near an end portal

-Jump in and before you enter open your inventory

-Game Crash

OR

Go into a non-activated end portal with your inventory open and have someone else in the world activate it. Your game will crash.