/datum/greyscale_layer/icon_state runs icon_states

[Mothblocks]

/datum/greyscale_layer/icon_state/Initialize(icon_file)
	. = ..()
	var/list/icon_states = icon_states(icon_file)
	if(!(icon_state in icon_states))
		CRASH("Configured icon state \[[icon_state]\] was not found in [icon_file]. Double check your json configuration.")

This code should only run behind a focus test.

However, just doing that would make the artist UX noticably worse. To counter this, we should have a GAGS debug panel that would show you this same information when clicked. We can make this interface better than a general runtime ever could.