Trying to access array offset on value of type null

When b-blocks is used in combination with a plugin that alters the visible items in admin backend it produces the following error:

Trying to access array offset on value of type null in /wp-content/plugins/b-blocks/inc/AdminMenu.php on line 50

Trying to access array offset on value of type null in /wp-content/plugins/b-blocks/inc/AdminMenu.php on line 51

it can be solved if orderSubMenu function checks if the array-key exists before accessing it:

if (array_key_exists('b-blocks', $submenu)) {
            		$arr = array();
                    $arr[] = $submenu['b-blocks'][1]; // Help
                    $arr[] = $submenu['b-blocks'][2]; // Upgrade || Account
                    $submenu['b-blocks'] = $arr;
        }