Stats query doesn't work if a collection has no group

When executing the query for the statistics page, an exception is thrown when a collection with no group exists in ace

Exception Description: The column result [colgroup] was not found in the results of the query.
Query: ResultSetMappingQuery(sql="SELECT l1.date, c.name, c.colgroup, m.count, m.size FROM logevent l1 JOIN (   SELECT collection_id, min(date) AS date   FROM logevent   WHERE logtype = 20 GROUP BY collection_id) AS l2 ON l1.collection_id = l2.collection_id AND l1.date = l2.date AND l1.logtype = 20 JOIN (  SELECT id, name, colgroup FROM collection ) AS c ON l1.collection_id = c.id JOIN (   SELECT count(id) AS count, sum(size) AS size, parentcollection_id   FROM monitored_item   GROUP BY parentcollection_id) AS m   ON m.parentcollection_id = c.id ")