KafkaEx help - not able to get hello world going

Questions & Help Questions
,
1

I’m not able to get KafkaEx working. I’ve added the dependencies and use all the default configs, and I get the following when I run %> iex -S mix

[info] Application kafka_ex exited: KafkaEx.start(:normal, []) returned an error: an exception was raised:
    ** (Protocol.UndefinedError) protocol Enumerable not implemented for nil of type Atom. This protocol is implemented for the following type(s): Ecto.Adapters.SQL.Stream, Postgrex.Stream, DBConnection.Stream, DBConnection.PrepareStream, KafkaEx.Stream, HashSet, Range, Map, Function, List, Stream, Date.Range, HashDict, GenEvent.Stream, MapSet, File.Stream, IO.Stream
        (elixir) lib/enum.ex:1: Enumerable.impl_for!/1
        (elixir) lib/enum.ex:141: Enumerable.reduce/3
        (elixir) lib/enum.ex:3023: Enum.map/2
        (kafka_ex) lib/kafka_ex/server_0_p_10_and_later.ex:87: KafkaEx.Server0P10AndLater.kafka_server_init/1
        (stdlib) gen_server.erl:374: :gen_server.init_it/2
        (stdlib) gen_server.erl:342: :gen_server.init_it/6
        (stdlib) proc_lib.erl:249: :proc_lib.init_p_do_apply/3
** (Mix) Could not start application kafka_ex: KafkaEx.start(:normal, []) returned an error: an exception was raised:
    ** (Protocol.UndefinedError) protocol Enumerable not implemented for nil of type Atom. This protocol is implemented for the following type(s): Ecto.Adapters.SQL.Stream, Postgrex.Stream, DBConnection.Stream, DBConnection.PrepareStream, KafkaEx.Stream, HashSet, Range, Map, Function, List, Stream, Date.Range, HashDict, GenEvent.Stream, MapSet, File.Stream, IO.Stream
        (elixir) lib/enum.ex:1: Enumerable.impl_for!/1
        (elixir) lib/enum.ex:141: Enumerable.reduce/3
        (elixir) lib/enum.ex:3023: Enum.map/2
        (kafka_ex) lib/kafka_ex/server_0_p_10_and_later.ex:87: KafkaEx.Server0P10AndLater.kafka_server_init/1
        (stdlib) gen_server.erl:374: :gen_server.init_it/2
        (stdlib) gen_server.erl:342: :gen_server.init_it/6
        (stdlib) proc_lib.erl:249: :proc_lib.init_p_do_apply/3