} else if (!utils.isString(index) && !utils.isObject(index)) {
        throw new IllegalArgumentError(errorPrefix + 'index: Must be a string or an object!', { actual: typeof index, expected: 'string|object' });
      } else if (!utils.isObject(options)) {
        throw new IllegalArgumentError(errorPrefix + 'options: Must be an object!', { actual: typeof options, expected: 'object' });
      }