Error after Sphero Client call

Sphero Agent Error

=ERROR REPORT==== 31-Mar-2015::15:21:39 ===
** Generic server <0.156.0> terminating 
** Last message in was {roll,500,170}
** When Server state == #{'__struct__' => 'Elixir.Sphero.Client.State',
                          device => <0.157.0>,
                          seq => 0}
** Reason for termination == 
** {badarg,[{erlang,apply,
                    [#{'__struct__' => 'Elixir.Sphero.Client.State',
                       device => <0.157.0>,
                       seq => 0},
                     seq,[]],
                    []},
            {'Elixir.Sphero.Client',do_request,2,
                                    [{file,"lib/sphero/client.ex"},{line,41}]},
            {gen_server,handle_msg,5,[{file,"gen_server.erl"},{line,580}]},
            {proc_lib,init_p_do_apply,3,[{file,"proc_lib.erl"},{line,237}]}]}
** (exit) exited in: GenServer.call(#PID<0.156.0>, {:roll, 500, 170}, 5000)
    ** (EXIT) an exception was raised:
        ** (ArgumentError) argument error
            :erlang.apply(%Sphero.Client.State{device: #PID<0.157.0>, seq: 0}, :seq, [])
            (sphero) lib/sphero/client.ex:41: Sphero.Client.do_request/2
            (stdlib) gen_server.erl:580: :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