errors: add comments about falsy error types

Some error types are not properly set. This adds comments which
ones are probably falty and to what they should be set instead.

Backport-PR-URL: https://github.com/nodejs/node/pull/19244
PR-URL: https://github.com/nodejs/node/pull/18857


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>