count_user_posts() does not check for empty $userid

[Ste_95]

If count_user_posts() is called with a NULL $userid, it will return the total count of all site posts, rather than 0 or some error.

I think this should not be expected behavior and we should bail early if $userid is NULL. This happens because get_posts_by_author_sql() then ignores the $userid arg if it is NULL.

https://core.trac.wordpress.org/browser/tags/4.9.6/src/wp-includes/user.php#L347

[krynes]

I think this is solution

[krynes]

I think this is solution

[krynes]

This is solution, the best option

[Ste_95]

I don't think we should check for is_user_logged_in(), since get_posts_by_author_sql() doesn't change its behavior in case the user is logged in.