I was leading 2 Llamas around, 1 I had leashed, the other was following the previous one. Then the game crashed.
The crash report mentions Ender Boxes. I had placed two red ones previous to this event, they each had the same contents (17 bones) because I had Ctrl+Middle Clicked one to get the same NBT data and I placed it again.
Attachments
Comments

[media]

Cannot get property atr{name=facing, clazz=class cv, values=[down, up, north, south, west, east]} as it does not exist in atf{block=minecraft:air, properties=[]}
I had the same crash as well but it happened pretty randomly and only happened once (probably no llamas involved).