Check this error

https://github.com/firebase/firebase-js-sdk/issues/283


In "App/Datapoint/Firebase.js" add the following code on start

const originalSend = XMLHttpRequest.prototype.send;
XMLHttpRequest.prototype.send = function(body) {
  if (body === '') {
    originalSend.call(this);
  } else {
    originalSend.call(this, body);
  }
};