Cannot pickup chest when killed a mule or donkey

I was test with some Mule and Donkey(at v.16w32a when you ride Mule or Donkey, it crash the game)

It was great ! It won't crash the game when I ride it, but what happen is when i put a chest in to Mule or Donkey, it still work, but when I killed them the chest will drop out, BUT I can pick it up, so to remove it i have to use the /kill command or use flint and steal

one chest is actually important, because it require 8 wood plank to craft it

that it, please help to make Minecraft more better