Minecraft:inventory component in custom entities is broken. Type 'horse' isn't working.

Partner Rank: 1-Critical updated

Partner Team Reporting: Panascais

Verification build: Version 1.16.20.54 build 4417012, Win10

Regression build: Unknown

Description:
The 'horse' type in the component 'minecraft:inventory' is not working and when using it, also it breaks the game by not letting you enter any other inventory after trying to. Other types do in fact work, but they are not as customisable as the one used by the horse and mule.

Summary:
Minecraft:inventory component in custom entities is broken. Type 'horse' isn't working.

Impact:
The 'horse' type is the one with the most custom usability. This type not working decreases production quality when using inventories on custom entites and live content is broken now.

Repro Steps:
1. Create custom entity with inventory component using the 'horse' type.
2. Add minecraft:is_chested component to the custom entity.
3. Enter a world with selected behaviour pack.
4. Try to enter the entities inventory.
5. Try to enter any other inventory including chests and player inventory itself.

Observed Result:
Inventory does not open and any other inventories, including player inventory and chests, are not accessible after that.

Expected Result:
Inventory is accessable with the correct displayed slots and any other inventory is accessible aswell.

Screenshots/Videos attached: No

Notes: This report potentially has to do with 'MCM-1147' since I also addressed a bug that has to do with the minecraft:inventory component.
Updating this bug as it affects live content, at least 'Jetpacks' by AriaCreations, and potentially lots of other live content.

update Adding the minecraft:equipable component makes you able to enter the inventory but it still doesn't work as intended