So, you're saying you expect libraries that don't have a generic 4xx "Oops, my bad, dev please handle it" error case to be bothered by the existence of 418 in a

So, you're saying you expect libraries that don't have a generic 4xx "Oops, my bad, dev please handle it" error case to be bothered by the existence of 418 in any way, shape or form? I think you're barking up the wrong tree.