Error

** (exit) exited in: GenServer.call({TermuxSmsCli.Fetcher, :"[email protected]"}, :threads, 5000)
    ** (EXIT) an exception was raised:
        ** (FunctionClauseError) no function clause matching in TermuxSmsCli.Fetcher.handle_call/3
            (termux_sms_cli) lib/termux_sms_cli/fetcher.ex:13: TermuxSmsCli.Fetcher.handle_call(:threads, {#PID<0.173.0>, #Reference<0.507083762.647495681.6201
1>}, nil)                                                                                                                                                     
            (stdlib) gen_server.erl:661: :gen_server.try_handle_call/4
            (stdlib) gen_server.erl:690: :gen_server.handle_msg/6
            (stdlib) proc_lib.erl:249: :proc_lib.init_p_do_apply/3
    (elixir) lib/gen_server.ex:989: GenServer.call/3

fetcher.ex

defmodule TermuxSmsCli.Fetcher do
  use GenServer
  use Bitwise

  def start_link(opts) do
    GenServer.start_link(__MODULE__, :ok, [name: TermuxSmsCli.Fetcher] ++ opts)
  end

  def init(:ok) do
    {:ok, nil}
  end

  def handle_call(:fetch, _From, nil) do
    {reply, 0} = System.cmd("termux-sms-list", ["-l", "#{1 <<< 30}"])
    {:reply, reply |> Jason.decode!, nil}
  end

  def fetch() do
    GenServer.call(TermuxSmsCli.Fetcher, :fetch)
  end

  def fetch(node) do
    GenServer.call({TermuxSmsCli.Fetcher, node}, :fetch)
  end
end

thread.ex

defmodule TermuxSmsCli.Thread do
  use GenServer
  use Bitwise

  def start_link(opts) do
    GenServer.start_link(__MODULE__, :ok, opts)
  end

  def init(:ok) do
    {:ok, nil}
  end

  def handle_call(:threads, _From, nil) do
    messages = TermuxSmsCli.Fetcher.fetch()
    {:reply, messages |> Enum.reduce(MapSet.new(), fn %{"threadid" => tid}, set -> set |> MapSet.put(tid) end), nil}
  end

  def threads() do
    GenServer.call(TermuxSmsCli.Thread, :threads)
  end

  def threads(node) do
    GenServer.call({TermuxSmsCli.Fetcher, node}, :threads)
  end
end