unstructured

a80decdb - fix [NEX-28]: file_type is None for result_file_type in chunker partition json (#4022)

fix [NEX-28]: file_type is None for result_file_type in chunker partition json (#4022) ### Summary `'NoneType' object has no attribute 'partitioner_shortname'` due to `result_file_type = self._disambiguate_json_file_type` could return None for file type