Better error message if javascript is unable to fetch results

[bwitt]

If the javascript on the web status page cannot fetch the status of the queue, all that is shown to the user is "..." under each of prep, que, run, etc.

Suggest adding some text to make clear what is happening or supposed to be happening.

[sodabrew]

This little JS snippet looks useful:
https://www.christianheilmann.com/2015/12/25/detecting-adblock-without-an-extra-http-overhead/

var test = document.createElement('div');
test.innerHTML = ' ';
test.className = 'adsbox';
document.body.appendChild(test);
window.setTimeout(function() {
  if (test.offsetHeight === 0) {
    document.body.classList.add('adblock');
  }
  test.remove();
}, 100);