code: function createErrInfo(opts, req) {
      assert.object(opts, 'opts');
      assert.object(req, 'req');
  
      return {
          // port and address can both be unpopulated - fall back on null so
          // that they can both be null (instead of req.remoteAddress
          // defaulting to undefined)
          address: req.remoteAddress || null,
          fullUrl: fullRequestUrl(opts),
          method: opts.method,
          port: opts.port
      };
  }
docs: create an info object for use with verror given the opts object used to
  issue the original request, along with the request object itself.
  @private
  @function createErrInfo
  @param {Object} opts an options object
  @param {Object} req a request object
  @returns {Object}