The node to traverse cannot be null Hibernate SQL

Question

I'm using hibernate to run the following SQL query:

SELECT thi 
FROM track_history_items thi 
JOIN artists art 
  ON thi.artist_id = art.id 
WHERE thi.type = "TrackBroadcast" 
GROUP BY art.name 
ORDER thi.createdAt DESC

However, I keep getting the error message "Node to traverse cannot be null!" Anyone have any idea what might be causing this?