Healing/repairing iron golem with an iron ingot right as they die causes them to come back weirdly

Summary:
I was trying to heal an iron golem to see how much Iron it takes for one Iron golem to one verses one a warden. I think I might have healed it right when it was about to die and now it glows red and won't die

Steps to reproduce:

1. Summon an iron golem.

2. Kill the iron golem.

3. During the death animation, heal an iron golem with an iron ingot.

Observed results:
The iron golem became alive and began to shake (death animation).

Expected results:
An iron golem cannot be healed with an iron ingot when it is already dead.