When debugging JS in chrome dev-tools console I get an error...

[polonus]

The error is "Failed to load response" for rss.png & twitter.png
Also this error is in

function scheduleTask(task) {
    XMLHttpRequest[XHR_SCHEDULED] = false;
    var data = task.data;
    // remove existing event listener
    var listener = data.target[XHR_LISTENER];
    if (listener) {
        data.target.removeEventListener('readystatechange', listener);
    }
    var newListener = data.target[XHR_LISTENER] = function () {
        if (data.target.readyState === data.target.DONE) {
            // sometimes on some browsers XMLHttpRequest will fire onreadystatechange with
            // readyState=4 multiple times, so we need to check task state here
            if (!data.aborted && XMLHttpRequest[XHR_SCHEDULED] && task.state === 'scheduled') {
                task.invoke();
            }
        }
    };
    data.target.addEventListener('readystatechange', newListener);
    var storedTask = data.target[XHR_TASK];
    if (!storedTask) {
        data.target[XHR_TASK] = task;
    }
    sendNative.apply(data.target, data.args);  ///' error message Failed to load resource: net::ERR_CONNECTION_REFUSED  ////
    XMLHttpRequest[XHR_SCHEDULED] = true;
    return task;
}

See: https://jsfiddle.net/ysangkok/sJxXk/86/
The issue discription: https://github.com/github/fetch/issues/83

For err_connection_refused -> https://medium.com/@sslsecurity/what-is-err-connection-refused-error-in-chrome-and-how-to-fix-it-7bfdb1ea2b61

Interesting instruction video on debugging JavaScript in Google Chrome by Gordon Zhu (info credits there) you will find here:
https://www.youtube.com/watch?v=zv_aOlH8S_o

polonus (volunteer website security analyst and website error-hunter)