The error event on `<source>` elements doesn't work. Looking at #4370, it seems like there is an `onError` for `<video>` but I can't tell if that's supposed to work for `<source>` too.

The error event is useful so I can deduce which format the browser is using.

if (internalInstance) {
    var owner = internalInstance._currentElement._owner || null;
    if (owner) {
      var name = owner.getName();
      if (name) {
        return ' This DOM node was rendered by `' + name + '`.';
      }
    }
  }
  return '';
}
function friendlyStringify(obj) {