Appsignal: Handling exceptions in plug in endpoint

this_doesnt_work.ex

  @impl Plug
  # naively copied version from Appsignal.Plug
  def call(%{path_info: ["webhook", "my-webhook"]} = conn, opts) do
    Appsignal.instrument(fn span ->
      _ = Appsignal.Span.set_namespace(span, "http_request")

      try do
        MyUnderlyingPlug.call(conn, opts)
      catch
        kind, reason ->
          stack = __STACKTRACE__

          _ =
            # handle error condensed a bit, as the Webhook will never raise a WrapperError
            span
            |> Appsignal.Span.add_error(kind, reason, stack)
            |> Appsignal.Tracer.close_span()

          Appsignal.Tracer.ignore()
          :erlang.raise(kind, reason, stack)
      end
    end)
  end

this_works.ex

  @impl Plug
  def call(%{path_info: ["webhook", "my-webhook"]} = conn, opts) do
    span =
      "http_request"
      |> Span.create_root(self())
      |> Span.set_name("MyApp.WebhookPlugWrapper#call")

    conn =
      try do
        MyUnderlyingPlug.call(conn, opts)
      catch
        kind, reason ->
          Span.add_error(span, kind, reason, __STACKTRACE__)

          conn
          |> Plug.Conn.send_resp(500, "Internal Server Error")
          |> Plug.Conn.halt()
      end
      
    Span.close(span)

    conn
  end