Description:
When a pregnant cat's timer runs out and her kittens are supposed to spawn, the world/server crashes and becomes corrupted.
This is either caused by the father's data not being saved properly when they mate, or the father's data is not being reinitialized properly for the kitten's data.

To Reproduce:

1. Get female cat pregnant
2. Wait for pregnancy timer to hit 0
3. Crashes immediately

Expected behavior:
When a female cat successfully breeds with a male cat, his nbt data is written to her data and later referenced at the end of EntityCatAIBirth for setting up the kitten's data in order to spawn.

Crash Report: https://pastebin.com/8V2WuWSx

Minecraft version: 1.12.2
Forge version: 14.23.5.2838
Mod version: 0.0.1.2

Additional Information:
Works as intended with both forge versions 14.23.5.2768 and 14.23.5.2831

Fixed, will close when fixed version is released just in case.

Can finally close this.