Works but undefined index notice

If running PHP 7+, you can get an undefined index notice on line 408 of class-heirary.php.

A better way of defining $post_types_to_hide on line 408 would be to do the following:

/**
 *  Just create an empty array
 */

$hideFromMenuFix = array();

if (isset($this->settings['hidden_from_admin_menu'])) {
 $post_types_to_hide = array_intersect( $this->post_types, (array) $this->settings['hidden_from_admin_menu'] );
 } else {
 // if not set, use the blank array
 $post_types_to_hide = array_intersect( $this->post_types, (array) $hideFromMenuFix );
 }

Hope this helps!