These new error messages were referring to formatDate instead of
formatNum.
Change-Id: Ic20a5a5515ee55d46087449627138cc779909ec3
Follow-up: Ib7706ad40f7ee2da6ab7c6b2dab6ae8d129dab52
Bug: T268758
The core formatNum method only works on strings which pass `is_numeric`,
not NaN and +/- infinity.
Bug: T267587
Change-Id: Ib7706ad40f7ee2da6ab7c6b2dab6ae8d129dab52