adding a capability to a non-existing role gives warnings

[opajaap]

When a plugin does something like this:

global $wp_roles;
$wp_roles->add_cap('a_nonexistent_role', 'any_capability');

no error (about the non-existance of the role) is displayed.
However, each subsequent page request produces this errormessage:

Notice: Undefined index: name in /mnt/web7/...../wordpress/wp-includes/capabilities.php on line 113

Debug is on: define('WP_DEBUG', true); in wp-config.php

This patch i invented myself already.
I would like a solution to add_cap(), and a way to remove the invalid (nameless) role i seem to have created.

18461.2.patch​ introduces isset() checks for add_cap() and remove_cap().

I don't think we should automatically remove an invalid role here. It can be removed with remove_role(), in the same way it was added.

This is small / useful / avoids PHP notice

In 22354:

Fix a PHP Notice when attempting to Add or remove capabilities from nonexistant roles. Props SergeyBiryukov. Fixes #18461