I tested this on the beta build (Build 1604) and current live (Build 1604). One of my friend's avatar when trying to load, instantly crashes my game, and only my game.

To make sure it was their avatar, I asked them to switch to another, joined the world and it was fine. Then I asked them to switch back and instantly crashed. They gave me their avatar ID of the avatar affecting me and i'm providing my logs.

Avatar: avtr_37be9519-a3fb-44db-af97-d6062db0fe13