The response from proxy is a webdriver response, which means that `err` can be null even if there was a selenium error returned (this will then be denoted by a `res.status` > 0). What you probably want is:

```js
if (err || res.status !== 0) {
  findCb(false, err, res);
} else {
  findCb(true, err, res);
}
```