IO operation on closed file

def query(self, query_str):
    qp = QueryParser("content", ix.schema)
    q = qp.parse(unicode(query_str))
    with self.ix.searcher() as searcher:
        results = searcher.search(q)
    return results
and using results later in some other code raises this error,
  File "main.py", line 62, in <module>
    main()
  File "main.py", line 57, in main
    print result
  File "/usr/lib/python2.7/dist-packages/whoosh/searching.py", line 1469, in __repr__
    return "<%s %r>" % (self.__class__.__name__, self.fields())
  File "/usr/lib/python2.7/dist-packages/whoosh/searching.py", line 1377, in fields
    self._fields = self.searcher.stored_fields(self.docnum)
  File "/usr/lib/python2.7/dist-packages/whoosh/filedb/filereading.py", line 136, in stored_fields
    return dict(item for item in iteritems(self._stored[docnum])
  File "/usr/lib/python2.7/dist-packages/whoosh/codec/whoosh2.py", line 899, in __getitem__
    dbfile.seek(start)
ValueError: I/O operation on closed file