Can't clear a numeric property value

[j-mok]

Once I enter something in the value box of a numeric product property, I'm basically stuck with that or other valid numeric value. If I clear the input box, it immediately becomes invalid and I can't save it (or any other edits in the properties blade). This happens even if I clear the field right after I entered a value for the first time, without closing the blade and persisting the product. I need a way to clear a numeric property value, effectively taking it back to the original state when the product didn't have that property value set at all.