whoosh traceback

  File "src/thirdparty/whoosh/searching.py", line 786, in search
    self.search_with_collector(q, c)
  File "src/thirdparty/whoosh/searching.py", line 819, in search_with_collector
    collector.run()
  File "src/thirdparty/whoosh/collectors.py", line 143, in run
    self.set_subsearcher(subsearcher, offset)
  File "src/thirdparty/whoosh/collectors.py", line 919, in set_subsearcher
    WrappingCollector.set_subsearcher(self, subsearcher, offset)
  File "src/thirdparty/whoosh/collectors.py", line 621, in set_subsearcher
    self.child.set_subsearcher(subsearcher, offset)
  File "src/thirdparty/whoosh/collectors.py", line 1138, in set_subsearcher
    WrappingCollector.set_subsearcher(self, subsearcher, offset)
  File "src/thirdparty/whoosh/collectors.py", line 621, in set_subsearcher
    self.child.set_subsearcher(subsearcher, offset)
  File "src/thirdparty/whoosh/collectors.py", line 171, in set_subsearcher
    self.matcher = self.q.matcher(subsearcher, self.context)
  File "src/thirdparty/whoosh/query/compound.py", line 211, in matcher
    m = self._matcher(subs, searcher, context)
  File "src/thirdparty/whoosh/query/compound.py", line 270, in _matcher
    context, q_weight_fn)
  File "src/thirdparty/whoosh/query/compound.py", line 226, in _tree_matcher
    subms = [q.matcher(searcher, context) for q in subs]
  File "src/thirdparty/whoosh/query/compound.py", line 211, in matcher
    m = self._matcher(subs, searcher, context)
  File "src/thirdparty/whoosh/query/compound.py", line 369, in _matcher
    scale=self.scale).matcher(searcher, context)
  File "src/thirdparty/whoosh/query/compound.py", line 211, in matcher
    m = self._matcher(subs, searcher, context)
  File "src/thirdparty/whoosh/query/compound.py", line 384, in _matcher
    m = matching.CoordMatcher(m, scale=self.scale)
  File "src/thirdparty/whoosh/matching/wrappers.py", line 536, in __init__
    self._maxqual = child.max_quality()
  File "src/thirdparty/whoosh/matching/binary.py", line 80, in max_quality
    q += self.a.max_quality()
  File "src/thirdparty/whoosh/matching/mcore.py", line 616, in max_quality
    return self.scorer.max_quality()
  File "src/thirdparty/whoosh/scoring.py", line 119, in max_quality
    raise NotImplementedError(self.__class__.__name__)
NotImplementedError: FunctionScorer