NaN% is the percentage you get when you try to turn the fraction sitemap.xml/undefined into a percent.
The fraction itself doesn’t have a real value because you’re dividing by something that isn’t defined. In math, any number divided by “undefined” results in an indeterminate form, which computers often label as NaN (Not a Number).
Since the result is not a real number, the percentage also shows up as NaN%. This tells you that the calculation can’t produce a meaningful numeric answer, and you’ll need a proper denominator before you can get a real percentage.
