After feeding two tamed llamas several hay bales while Strength
is 0 (which is the default when summoned), the moment they began to breed, the game crashes.
Crashes when bred:
/summon minecraft:llama ~ ~1 ~ {Tame:1b,Strength:0}
Does not crash:
/summon minecraft:llama ~ ~1 ~ {Tame:1b,Strength:1}
Crashed after they tried breeding (fed with hay bale in survival).