@julesh : I know I wasn't part of the original conversation, but that all sounds correct to me.
Since the question about quantity is, as with a scope error, whether it's 0 or not, I'd still think of this quantity error as more like a scope error, just in reverse. In a regular scope error, x is supposed to be in scope but it's not; in this reverse scope error, x isn't supposed to be in scope but it is.