Fatal Error on Admin Notice Feed

[ocean90]

If the feed, which I set for the 'Admin Notice Feed', doesn't exist or has an errror I get this message on Dashboard:

Fatal error: Call to undefined method WP_Error::get_item() in /var/www/web31/html/wp-admin/includes/ms.php on line 629

[nacin]

Nice catch, we should be checking for is_wp_error() (explanation in #12059).

Patching up.

[dd32]

(In [12965]) Cleanup admin_notice_feed(). Props nacin. Fixes #12138