Server crash on (SELECT ... INNER JOIN ... LIMIT 20) ORDER BY ... COLLATE ...

CREATE TABLE `tttttt` (`id` int(11) NOT NULL AUTO_INCREMENT, PRIMARY KEY (`id`)) ENGINE=MyISAM;

CREATE TABLE `sssss` (`id` int(11) NOT NULL, `t` varchar(100) NOT NULL) ENGINE=MyISAM;

(SELECT `t` FROM `tttttt` a INNER JOIN `sssss` b ON a.id=b.id LIMIT 20) ORDER BY `t` COLLATE utf8mb4_general_ci DESC;