Deleting vanilla parts makes the game unable to apply the resource pack

[SumRandomDewd]

So, I tried to delete a vanilla part in an entity model, and when I was going to test the resource pack models, the game was unable to reload resource packs, and a notification popped in the top-right corner of the screen. I don't know if this is intentional, but if it isn't, please fix this because it's annoying.