Fix DuplicateCompatError constructor argument (#16264)
Fix DuplicateCompatError constructor argument (#16264)

If actually used, an error is thrown because `feature` is undefined,
which is very unhelpful.
mdn/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data,chrisdavidmills/browser-compat-data