code: function onClientError(err, res) {
      if ((err || {}).name === 'SizeLimitExceededError') {
        onSearchEnd(res);
        return;
      }
  
      client.unbind();
      log.error(err, '[%s] An error occurred performing the requested LDAP search on %s (%j)',
                (err || {}).errno || 'UNKNOWN', baseDN, opts);
      if (callback) callback(err);
    }
docs: Occurs when a client / search error occurs.
  @param {Object} err The error object or string.
  @param {Object} res The optional server response.