Unknown column 'a.ordering' in 'order clause'
$results = $db->setQuery($query)->loadObjectList();
Open PhpMyAdmin > SQL and type this:
ALTER TABLE `#__menu_types` ADD COLUMN `ordering` int NOT NULL DEFAULT 0 AFTER `client_id` /** CAN FAIL **/;
UPDATE `#__menu_types` SET `ordering` = `id` WHERE `client_id` = 0;
You're welcome, @sirius82 😊
I have no idea why it was missing.