The bug

When using commands to give items with an invalid model specified, the missing model will be used.

This is inconsistent with the existing "custom_model_data" component, which uses the default model for that item as a fallback if there is no special model associated with a given value.

How to reproduce

1. /give @s minecraft:stone[minecraft:custom_model_data=2147483647]

2. Note how this just looks like normal stone, as expected

3. /give @s stone[item_model="minecraft:nonexistent_model"]

4. Note the huge missing model

Expected results

If an item specifies a nonexistent model, it should use the default model for that item as a fallback instead of the missing model. The missing model should only appear in cases where resource packs are misconfigured, not when using commands with only the default resource pack active.

Actual results

Big missing textures, instead of the default model for that item.