ext: missing return
ext: missing return

* FIX Fixes missing return statement in
  `_FilesRESTState.record_file_factory()`.

Signed-off-by: Samuele Kaplun <2e218f779e12714c314fad8ebf6b3041daa21337@cern.ch>

inveniosoftware/invenio-files-rest,inveniosoftware/invenio-files-rest