[Suggestion] Referencing texture variables across texture atlases is not allowed in 1.21.11(25w45a)

[MysteryPSD]

Detailed description of your suggestion

Since 1.21.11 25w45a, the item models can only use the textures in "item" or "block" texture atlas, and using a texture from "item" texture atlas and a texture from "block" texture atlase is not allowed any longer. The block models can only use the textures in "block" texture atlas.

It means that the models which contains the texture variable like "0": "block/xxx" and the texture variable like "1": "item/xxx" won't be loaded by Minecraft correctly.

This model used a block texture and an item texture, and its format was "1.21.11". It was invalid. I suggest that when loading models like my example, Blockbench should issue a warning.