errors: remove duplicate error definition

Also fixes error being (now!) properly thrown by alphabetize-errors.

also properly enable lint rule

Was not using proper magic comment syntax before!

-URL: https://github.com/nodejs/node/pull/15307


Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>