Indicate problems with textures/meshes

[cohaereo]

Option 1 (in your face)

Option 2 (subtler, but leaves a pointless black void)

Might also go for red instead of yellow since it's usually related to screwed up imports.
Additionally, these tiles will have a tooltip describing the exact reason

[cohaereo]

Probably going for option 2 since it's off centered and looks more out of place.
Additionally we'll also add a checkbox filter to filter out failed meshes, but have them shown by default

[cohaereo]

Extending this issue to include textures and fatal errors. I'm experimenting with an IdentifiableResult type that allows us to have a result that contains a hashcode no matter the result's variant.

Errors during read should result in a red icon, and replace the tooltip with the error's description. Non-fatal issues should be represented with a yellow triangle, and the warnings should be appended to the existing tooltip