Warden indefinitely roars when the attack target is invulnerable

Warden indefinitely roars when the attack target is invulnerable.
And after a period of time, stuck in place and no longer looking for new targets.

1. Summon a warden.
2. Use the following command:

    /summon pig ~ ~ ~ {Invulnerable:1b} 

3. Notice that the warden starts to indefinitely roar.