Steps to reproduce

1. Go to the nether.
2. Relog.
3. Spawn a zombie villager.
4. Cure the zombie villager (weakness potion + golden apple).

Expected results

The zombie villager gets red particles, and after waiting a few minutes it converts to a villager.

Actual results

The zombie villager gets red particles, and after waiting a few minutes the game crashes. Whenever you try to open that world again, the game crashes. So, the world is permanently broken.

I have a villager converter in the nether where I zombify a villager, shoot it with a weakness tipped arrow and then I heal it with a golden apple. After a few minutes of the zombie shaking it the game crashes and whenever I try to load back into the world it crashes. The world is purely survival, the zombie villager was in a minecart when I tried to cure it, and the zombie villager was a librarian.