code: function errorLogger( err, req, res, next ) {
    var error = getServerError( err, req )
  
    console.error( { error: error } )
  
    if ( error.statusCode !== 404 ) {
      console.error( err.stack )
    }
  
    res.status( error.statusCode ).send( getResponseMessage( err, req, process.env.NODE_ENV ) )
  }
docs: this middleware needs to be added after all “non-error” middleware in the application.
  it assumes that if the application got here, an error was sent via next( err ).
  
  @link http://expressjs.com/en/guide/error-handling.html
  
  @param {Error} err
  @param {number} err.status
  @param {number} err.statusCode
  
  @param {IncomingMessage} req
  
  @param {ServerResponse} res
  @param {Function} res.send
  
  @param {Function} next
  
  @returns {undefined}