Error when using affjax on node

I have this small program that makes an HTTP request and prints the result:

module HttpClient where

import Prelude

import Data.Either (Either(..))
import Data.HTTP.Method (Method(..))
import Effect (Effect)
import Effect.Aff (Fiber, launchAff)
import Effect.Class (liftEffect)
import Effect.Console (log)
import Network.HTTP.Affjax as AX
import Network.HTTP.Affjax.Response as AXRes

main :: Effect (Fiber Unit)
main = launchAff $ do
  let req = AX.defaultRequest { url = "", 
                                method = Left GET }
  res <- AX.affjax AXRes.string req
  liftEffect $ log $ "Your IP address: " <> res.response

When I run this program using pulp run -m HttpClient, I sometimes get this error:

                throw util.fromLeft(step);

Error: AJAX request failed: GET
    at XMLHttpRequest.xhr.onerror (/Users/fhsu/work/purescript-examples/output/Network.HTTP.Affjax/foreign.js:57:17)
    at XMLHttpRequestEventTarget.dispatchEvent (/Users/fhsu/work/purescript-examples/node_modules/xhr2/lib/xhr2.js:64:18)
    at XMLHttpRequest._dispatchProgress (/Users/fhsu/work/purescript-examples/node_modules/xhr2/lib/xhr2.js:555:12)
    at XMLHttpRequest._onHttpRequestError (/Users/fhsu/work/purescript-examples/node_modules/xhr2/lib/xhr2.js:545:12)
    at ClientRequest.<anonymous> (/Users/fhsu/work/purescript-examples/node_modules/xhr2/lib/xhr2.js:414:24)
    at ClientRequest.emit (events.js:182:13)
    at TLSSocket.socketErrorListener (_http_client.js:382:9)
    at TLSSocket.emit (events.js:182:13)
    at emitErrorNT (internal/streams/destroy.js:82:8)
    at emitErrorAndCloseNT (internal/streams/destroy.js:50:3)

The weird thing is that it tends to fail on the first execution, but usually succeeds on successive attempts.