问当我在这个主管和工作人员的设置中调用start链接时，为什么我会得到一个ProtocolUndefined错误？

EN

defmodule MyDemo.Supervisor do
  use Supervisor

  ### API
  def start_link({_, _, _} = mod_func_arg) do
    Supervisor.start_link(__MODULE__, mod_func_arg)
  end

  def init({mod, func, arg} = x) do
    opts_worker = [restart: :permanent, function: func]
    children = worker(mod, arg, opts_worker)
    #opts = [strategy: :simple_one_for_one, max_restarts: 5, max_seconds: 5]
    opts = [strategy: :one_for_one, max_restarts: 5, max_seconds: 5]
    supervise(children, opts)
  end
end


defmodule MyDemo.Worker do
  use GenServer

  def start_link(_) do
    GenServer.start_link(__MODULE__, :ok, [])
  end

  def stop(pid) do
    GenServer.call(pid, :stop)
  end

  def handle_call(:stop, _from, state) do
    {:stop, :normal, :ok, state}
  end
end