Vex continue to attack their target after it has been killed

The bug

I was playing around with vexes and making them fight withers; i noticed that after all the withers had died, the vexes continued attacking where the withers used to be (though their attacking skin wasn't visible).

As I'm re-watching the video, they aren't necessarily attacking where the withers were, but it is still interesting behavior.

How to reproduce

1. Summon a snow golem.

   /summon snow_golem ~ ~ ~

2. Summon a group of vexes.

   /summon vex ~ ~ ~

3. Waiting for the snow golem to be killed.

4. Vexes will continue to attack where the snow golem died.