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);
};