When there is an empty list of users in user management (after a delete of a single user result for example). The below fatal query error is displayed.
JDatabaseMySQLi::query: 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 ') AND n.state >= 0 GROUP BY n.user_id' at line 3 SQL=SELECT n.user_id, COUNT AS note_count FROM `jos_user_notes` AS n WHERE n.user_id IN () AND n.state >= 0 GROUP BY n.user_id
The only remedy is to disable debug mode and clear the search result. It's due to the IN () (no results).