Simple Bandit HTTP Server test code giving "econnaborted" error?

I have started a basic HTTP Server as per the following tutorials:

#//PLUG MODULE FOR BANDIT  https://hexdocs.pm/plug/readme.html
defmodule MyPlug do
  import Plug.Conn

  def init(options) do
    # initialize options
    options
  end

  def call(conn, _opts) do
    conn
    |> put_resp_content_type("text/plain")
    |> send_resp(200, "Hello world")
  end
end

#//MAIN MODULE
defmodule ServerTest do

def startHttpServer do
    IO.puts("Try Start HTTP Server");
    webserver = {Bandit, plug: MyPlug, scheme: :http, port: 4000 }
    supervisorOpts = [strategy: :one_for_one ]
    {:ok, _} = Supervisor.start_link([webserver], supervisorOpts)
    IO.puts("Plug now running on localhost:4000");
    #Process.sleep(:infinity)
  end

end

This works, in that if I run the project and then ServerTest.startHttpServer() and go to localhost:4000 I get a “Hello world” back. But I am also getting this:

21:11:37.278 [error] GenServer #PID<0.554.0> terminating
** (stop) :econnaborted
Last message: {:tcp_error, #Port<0.3>, :econnaborted}
State: {%ThousandIsland.Socket{socket: #Port<0.3>, transport_module: ThousandIsland.Transports.TCP, read_timeout: 60000, silent_terminate_on_error: false, span: %ThousandIsland.Telemetry{span_name: :connection, telemetry_span_context: #Reference<0.267163659.1006895106.157280>, start_time: -5764607406509056, start_metadata: %{telemetry_span_context: #Reference<0.267163659.1006895106.157280>, parent_telemetry_span_context: #Reference<0.267163659.1006895106.157220>, remote_address: {127, 0, 0, 1}, remote_port: 63311}}}, %{opts: %{http: [], http_1: [], http_2: [], websocket: []}, plug: {MyPlug, []}, handler_module: Bandit.HTTP1.Handler, http_1_enabled: true, http_2_enabled: true, requests_processed: 2}}

21:13:32.629 [error] ** (Bandit.HTTPError) Header read socket error: :closed

What does this all mean? What is wrong with the above code? Thanks for any help.

I find it funny also because I haven’t started any GenServer, so I presume this is a GenServer being started by Plug/Bandit? What is the problem?