Error in Flow

Questions / Help
1

I run two Flow process to parse XML file

     category_tree = File.stream!(file_path)
              |> Stream.drop(1)
              |> Stream.drop(-2000)
              |> SweetXml.stream_tags([:category])
              |> Flow.from_enumerable
              |> Flow.partition()
              |> Flow.map(fn {_, doc} ->
               #do some staff
              end)
        |> Enum.to_list


 File.stream!(file_path)
      |> Stream.drop(1)
      |> SweetXml.stream_tags([:offer])
      |> Flow.from_enumerable()
      |> Flow.partition()
      |> Flow.map(fn {_, doc} ->
        #do some staff
     end)
     |> Stream.run()

After done I got error:

12:05:25.135 [error] GenServer #PID<0.297.0> terminating (FunctionClauseError) no function clause matching in GenStage.Streamer.handle_info/2
lib/gen_stage/streamer.ex:27: GenStage.Streamer.handle_info({:wait, #Reference<0.536528267.1170472961.59133>}, #Function<24.40091930/1 in Stream.do_resource/5>)
lib/gen_stage.ex:2170: GenStage.noreply_callback/3
(stdlib) gen_server.erl:616: :gen_server.try_dispatch/4
(stdlib) gen_server.erl:686: :gen_server.handle_msg/6
(stdlib) proc_lib.erl:247: :proc_lib.init_p_do_apply/3 Last message: {:wait, #Reference<0.536528267.1170472961.59133>}

Thanks!