code: function respond (next) {
    return function sendResult (error, proxyObj) {
      if (error) { return next(error); }
  
      // TESTING HELPER ONLY
      if (proxyObj.options.shortCircuit) {
        return proxyObj.res.send({
          result: 'proxy-express set to short circuit. If this is not expected, please check your config'
        });
      }
  
      let proxyError = proxyObjErrors(proxyObj);
      if (proxyError) {
        return next(new Error(proxyError));
      } else if (!(proxyObj.result && proxyObj.result.response)) {
        return next(new Error('Proxy to ' + proxyObj.reqOpts.url + ' failed for an unkown reason'));
      } else {
        proxyObj.res.status(proxyObj.result.response.statusCode || 400).send(proxyObj.result.body);
      }
    };
  }
docs: respond with proxied result (fires at the end of all middleware execution)