title: Hibernate Error IllegalArgumentException: node to traverse cannot be null
body: <p>My <code>DELETE</code> query is failing.</p>
  
  <p><strong>Here's my code:</strong></p>
  
  <pre><code>String q = "SELECT p.id FROM Person p, DomainGroup g WHERE 
     p member of g.coordinators" + " AND g.id = :groupId 
     AND p.id = :personId";
  
  List&lt;Long&gt; test = getEntityManager()
    .createQuery(q).setParameter("groupId", followingId)
    .setParameter("personId", followerId).getResultList();
  
  log.debug("test = " + test);
  
  String deleteGroupCoordinatorQuery = 
    "DELETE FROM Person p, DomainGroup g WHERE p member 
       of g.coordinators" + " AND g.id = :groupId 
          AND p.id = :personId";
  
  List&lt;Long&gt; test = getEntityManager()
        .createQuery(deleteGroupCoordinatorQuery).setParameter
        ("groupId", followingId)
        .setParameter("personId", followerId).executeUpdate();
  </code></pre>
  
  <p><strong>output:</strong></p>
  
  <pre><code>test = [1,2,3]
  
  2012-10-26 13:44:56,437 ERROR org.company.commons.server.service.ServiceActionController - Error occurred performing transaction. java.lang.IllegalArgumentException: node to traverse cannot be null!
          at org.hibernate.hql.ast.util.NodeTraverser.traverseDepthFirst(NodeTraverser.java:55)
          at org.hibernate.hql.ast.QueryTranslatorImpl.parse(QueryTranslatorImpl.java:280)
          at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:182)
          at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:136)
  </code></pre>