Creating a new challenge on the test server results in an SQL error

A Database Error Occurred

Error Number: 1064

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'BY `source_data`' at line 1

SELECT `d1`.`did` AS source_data, `d2`.`did` AS `source_data_labeled`, `f1`.`name` AS `target_feature` FROM `dataset` `d1`, `dataset` `d2`, `data_feature` `f1`, `data_feature` `f2` WHERE `d1`.`did` = `f1`.`did` AND `d2`.`did` = `f2`.`did` AND `f1`.`name` = "class" AND `f2`.`name` = "class" AND `f2`.`NumberOfMissingValues` = 0 AND `f1`.`data_type` IN ("nominal") AND `f2`.`data_type` IN ("nominal") AND ((`d1`.`name` = "diabetes" AND `d1`.`version` = "1") ) AND 1ORDER BY `source_data`;

Filename: core/MY_Database_Read_Model.php

Line Number: 31

Start at core/MY_Database_Read_Model.php line 31 and reproduce the SQL error by creating a new challenge on the test server. Inspect how this query is assembled, then verify that the generated statement is valid MySQL and that challenge creation completes without the reported syntax error.