docs: function errorLogger(options) {
  
      ensureValidOptions(options);
  
      options.requestFilter = options.requestFilter || defaultRequestFilter;
      options.winstonInstance = options.winstonInstance || (new winston.Logger ({ transports: options.transports }));
  
      return function (err, req, res, next) {
  
          // Let winston gather all the error data.
          var exceptionMeta = winston.exception.getAllInfo(err);
          exceptionMeta.req = filterObject(req, requestWhitelist, options.requestFilter);
  
          // This is fire and forget, we don't want logging to hold up the request so don't wait for the callback
          options.winstonInstance.log('error', 'middlewareError', exceptionMeta);
  
          next(err);
      };
  }