EDIT (new comment because edit-period is long gone): It's not too severe an issue, maybe not one at all(?), at least in this concrete example, because after re

EDIT (new comment because edit-period is long gone): It's not too severe an issue, maybe not one at all(?), at least in this concrete example, because after removing the first occurrence of the hidden variable it now becomes a "not defined" real error and not just a warning in the second location.