doc: is the stability guarantee of err.code documented anywhere?

@jasnell

Surprisingly I cannot find in any significant places in https://github.com/nodejs/node/blob/master/doc/api/errors.md that err.code provides a stronger stability guarantee and should be preferred over parsing err.mesage. Am I missing something?

This is something that a lot of Node.js collaborators know, I am sure, but if we don't put it in a significant place in the docs (e.g. with examples), the users may not be able to be sure about that.

cc @jasnell

That whole section of the docs can use a pretty massive cleanup. I'm on it.

#24090

Fixed in 1368eb8

doc: update System Errors documentation