Swoosh isn't working straight from hexdocs

I was following this for sending Gmails from Phoenix whenever someone registers an account.

I modified my user controller to this

def create(conn, %{"_action" => "registered" , "user" => user_params} = params) do 
  Swoosh.Email.new() 
  |> Swoosh.Email.to({nil ,user_params["email"]}) 
  |> Swoosh.Email.from({"outsider", "outsideemail@home.here"}) 
  |> Swoosh.Email.subject("FINALLY!") 
  |> Swoosh.Email.html_body("<h1>FINALLY!</h1>") 
  |> Swoosh.Email.text_body("FINALLY!\n") 
  |> Pento.Mailer.deliver() 

  create(conn, params, "Account created successfully!") 
end

And my config/runtime.exs (for I got a warning from console that it’s better to place it there than config/config.exs)

config :pento, Pento.Mailer, 
  adapter: Swoosh.Adapters.Gmail, 
  access_token: {:system, "gmail-api-access-token-from-playground"}

I don’t get an email but I get this error

from console

[error] GenServer #PID<0.658.0> terminating
** (stop) :econnaborted
Last message: {:tcp_error, #Port<0.22>, :econnaborted}
State: {%ThousandIsland.Socket{socket: #Port<0.22>, transport_module: ThousandIsland.Transports.TCP, read_timeout: 60000, silent_terminate_on_error: false, span: %ThousandIsland.Telemetry{span_name: :connection, telemetry_span_context: #Reference<0.2682427495.2491154433.212811>, start_time: -8253868621053248, start_metadata: %{handler: Bandit.DelegatingHandler, remote_port: 55554, remote_address: {127, 0, 0, 1}, telemetry_span_context: #Reference<0.2682427495.2491154433.212811>, parent_telemetry_span_context: #Reference<0.2682427495.2491154435.210270>}}}, %{opts: %{http: [ ], websocket: `[ ]`, http_1: [ ], http_2: [ ]}, plug: {Phoenix.Endpoint.SyncCodeReloadPlug, {PentoWeb.Endpoint, [ ]}}, handler_module: Bandit.HTTP1.Handler, http_1_enabled: true, http_2_enabled: true, requests_processed: 40}}