maybe it'll work

code/modules/admin/topic.dm

@@ -2878,6 +2878,8 @@
 			return
 	if(SSdbcore.Connect())
 		var/datum/DBQuery/query_get_mentor = SSdbcore.NewQuery("SELECT id FROM [format_table_name("mentor")] WHERE ckey = '[ckey]'")
+		if(!query_get_mentor.warn_execute())
+			return
 		if(query_get_mentor.NextRow())
 			to_chat(usr, "<span class='danger'>[ckey] is already a mentor.</span>")
 			return