If a horse (not a donkey or a mule) is spawned with a chest (using commands), then if a player tries to put items into the horse's inventory, their game will crash.

What I expected to happen was...:
I expected a chested horse's inventory to work like one of a donkey or a mule with a chest equipped, that is, when an item is put into a slot, it does not result in crashing the game, and the item is stored in the horse's inventory.

What actually happened was...:
As soon as the player managing the horse's inventory clicks on a slot while having an item in their cursor, that is 'dragging' the item, the game crashes, sending a report with an 'Updating screen events' description, and a 'java.lang.ArrayIndexOutOfBoundsException: 8' issue.

Steps to Reproduce:
1. Summon a horse with /summon EntityHorse ~ ~ ~

2. Right click on the horse
3. Click on an item in your inventory, then move the cursor over and click on a slot in the horse's inventory.