kafka_ex producer error

config.exs

use Mix.Config

config KafkaEx,
 brokers: [{"localhost", 9092}]

gistfile1.txt

iex(1)> KafkaEx.metadata
%{brokers: %{0 => {"sf-jrotenb-mac", 9092}},
  topics: %{"BTBRWRJWSCUYLQPUXCSJ" => %{error_code: 0,
      partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]},
        1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]},
        2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}},
    "BZQYUODHAZQWITTZBLRX" => %{error_code: 0,
      partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]},
        1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]},
        2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}},
    "DRHXIHMYJUSDWSNKWEYV" => %{error_code: 0,
      partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]},
        1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]},
        2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}},
        # some topics trimmed
    "test" => %{error_code: 0,
      partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]},
        1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]},
        2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}}}
iex(2)> KafkaEx.create_worker(:pr)
{:ok, #PID<0.168.0>}
iex(3)> iex(3)> KafkaEx.produce("test", 0, "hey")   
** (exit) exited in: GenServer.call(KafkaEx.Server, {:produce, "test", 0, "hey", nil, 0, 100}, 5000)
    ** (EXIT) an exception was raised:
        ** (FunctionClauseError) no function clause matching in :gen_tcp.send/2
            (kernel) gen_tcp.erl:261: :gen_tcp.send(nil, <<0, 0, 0, 0, 0, 0, 0, 2, 0, 8, 107, 97, 102, 107, 97, 95, 101, 120, 0, 0, 0, 0, 0, 100, 0, 0, 0, 1, 0, 4, 116, 101, 115, 116, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 29, 0, 0, 0, 0, ...>>)
            (kafka_ex) lib/kafka_ex/server.ex:126: KafkaEx.Server.send_data/2
            (kafka_ex) lib/kafka_ex/server.ex:21: KafkaEx.Server.handle_call/3
            (stdlib) gen_server.erl:607: :gen_server.try_handle_call/4
            (stdlib) gen_server.erl:639: :gen_server.handle_msg/5
            (stdlib) proc_lib.erl:237: :proc_lib.init_p_do_apply/3
    (elixir) lib/gen_server.ex:356: GenServer.call/3
13:51:08.616 [error] GenServer KafkaEx.Server terminating
Last message: {:produce, "test", 0, "hey", nil, 0, 100}
State: {2, %{brokers: %{0 => {"sf-jrotenb-mac", 9092}}, topics: %{"BTBRWRJWSCUYLQPUXCSJ" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "BZQYUODHAZQWITTZBLRX" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "DRHXIHMYJUSDWSNKWEYV" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "IUEEGYQCCDZWBHJTZNDR" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "JHDGAQKHPHFMUWDMTKNN" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "KQVNDOEWUYZDJTOKXPJG" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "KWGLWSQMZOMKFVIXTZCR" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "LUSQIJEMCVYINROYFCMD" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "NGSOORJQTQRHHPRNBPFI" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "OKTQHMJMCDMJHOBYAYOG" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "SIEOFBHNXLAMLKEHZBYO" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "VEMGMWGEWHBCKRKNERLX" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "VUEXGQDTSNTCSMQYGAAV" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "adapter-updates" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "adserver-events" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "foo" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "food" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "haskakafka_tests" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}, "test" => %{error_code: 0, partitions: %{0 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 1 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}, 2 => %{error_code: 0, isrs: [0], leader: 0, replicas: [0]}}}}}, %{{"localhost", 9092} => #Port<0.5684>}, nil}
** (exit) an exception was raised:
    ** (FunctionClauseError) no function clause matching in :gen_tcp.send/2
        (kernel) gen_tcp.erl:261: :gen_tcp.send(nil, <<0, 0, 0, 0, 0, 0, 0, 2, 0, 8, 107, 97, 102, 107, 97, 95, 101, 120, 0, 0, 0, 0, 0, 100, 0, 0, 0, 1, 0, 4, 116, 101, 115, 116, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 29, 0, 0, 0, 0, ...>>)
        (kafka_ex) lib/kafka_ex/server.ex:126: KafkaEx.Server.send_data/2
        (kafka_ex) lib/kafka_ex/server.ex:21: KafkaEx.Server.handle_call/3
        (stdlib) gen_server.erl:607: :gen_server.try_handle_call/4
        (stdlib) gen_server.erl:639: :gen_server.handle_msg/5
        (stdlib) proc_lib.erl:237: :proc_lib.init_p_do_apply/3

nil
iex(4)> 
        
        

mix.exs

defmodule Loader.Mixfile do
  use Mix.Project

  def project do
    [app: :loader,
     version: "0.0.1",
     elixir: "~> 1.0",
     build_embedded: Mix.env == :prod,
     start_permanent: Mix.env == :prod,
     deps: deps]
  end

  def application do
    [applications: [:logger, :con_cache, :kafka_ex],
     mod: {Loader, []}]
  end

  defp deps do
    [{:con_cache, "~> 0.8.0"},
		 {:timex, "~> 0.13.4"},
		 {:kafka_ex, "~> 0.0.2"}]
  end
end