Painting (and perhaps more) / Data-Driven Fallback System

currently, as paintings (and other data-driven things, such as banners) are currently implemented, a missing texture checkerboard is displayed when you don't have the resource pack for them.

this is unfortunate, especially because there's already a system in place elsewhere that fixes this: the item model fallback system.

data-driven things should universally be able to define a fallback that's displayed instead in the event of absent resources. the custom thing should still exist and be accessible, but will display as something else until you get the resource pack.

this feedback actually ties in well to another feedback I submitted (https://feedback.minecraft.net/hc/en-us/community/posts/40524688312845-Custom-Data-Components-should-not-be-cleared-when-Datapacks-are-removed). this is a solution to the visual aspect of the problem! just display something else!

as an example, paintings could fallback to a defined default one (a 1x1 becoming aztec, for example). of course, a non-standard size will still display as something undesirable, probably a missing texture, or a stretched default one, but this is better than nothing. if I am to make another suggestion, I think the missing textures for non-standard paintings specifically should just be the back texture, as that's less of an eyesore. perhaps an option as one of the definable fallbacks?

minecraft's data-driven systems are so close to perfection, and this would take it one step closer to that goal.