Horse Spawners with SpawnPotentials or SpawnData Crash Minecraft

*What I expected to happen was...:
Horses should spawn.

*What actually happened was...:
Minecraft crashed.

Minecraft crashes on approaching a horse spawner with the SpawnData or SpawnPotentials NBT tags attached. This spawner did NOT have ActiveEffects NBT tags on it. (And therefore does not duplicate MC-16191)

Steps to Reproduce:
1. Create a spawner for EntityHorse
2. Add the SpawnData NBT tag.
3. Load the chunk containing said spawner.