There is a major bug in the game with the broken elytra. Obviously, using the elytra normally is perfectly fine, however, if you allow the elytra to break, the game will attempt to load the broken texture (as expected) but crash doing so... This was pretty sloppy, to be honest, with how easy it would be to pick up on... Happens to my friend as well on Windows 10, so it's not an isolated issue. And I did test it to ensure it wasn't an error caused by one of my resource packs, even default minecraft does it. This is a severe issue, PLEASE don't just let this blow off.