Trader llamas continue to spit after their target died

The bug

A wandering trader spawned in my world. I started playing around with it, and I summoned a zombie. The llama spit at the zombie, but kept spitting after the zombie was killed.

Note that the llama stopped when I logged out and back in.

How to reproduce

1. /summon trader_llama ~ ~ ~
2. /summon zombie ~ ~ ~

 - Llama spits at zombie
 - Zombie dies
 - Llama continues spitting at nothing