Yes, and when it does it is doing so in lieu of an error, and thus it is not returning the value of the setting. It does not mean the value taken on by the named parameter is NULL, which is not possible. i.e., SHOW will never produce NULL.
Hi,
OK, LGTM.
Thank you for the review. If you would like to add yourself as the reviewer and mark this ready to commit here is the commitfest entry. https://commitfest.postgresql.org/patch/5548/ David J.