Почему плагин express-message выдает ошибку «messages is not defined»?

Question

mustfuck @mustfuck

Express.js

Почему плагин express-message выдает ошибку «messages is not defined»?

Прохожу курс, делаю уроки. При добавление плагина express-messages столкнулся с проблемой. При запуске сервера, выдает ошибку

ReferenceError: /home/mustfuck/code/node/CmsShoopingCart/views/index.ejs:1
 >> 1| <%- include('_layouts/header'); -%>
    2| 
    3| <h1>Hello there</h1>
    4| 

/home/mustfuck/code/node/CmsShoopingCart/views/_layouts/header.ejs:51
    49|   
    50| 
 >> 51| <%- messages('messages', locals) %>

messages is not defined

делаю все по инструкции. В коде у автора, все тоже самое, что у меня. У него работает. На сайте плагина, написано, тоже что и у меня. Но у меня показывает ошибку messages is not defined Почему?

сайт плагина
https://github.com/visionmedia/express-messages

структура
views
-index.ejs
-messages.ejs
-_layouts
--header.ejs
app.js

app.js

var express = require('express');
var path = require('path');
var mongoose = require('mongoose');
var config = require('./config/database');
var bodyParser = require('body-parser');
var session = require('express-session');
var expressValidator = require('express-validator');
 
mongoose.Promise = global.Promise;
mongoose.connect(config.database);
var db = mongoose.connection;
//db.on('error', console.error.bind(console, 'connection error'));
db.once('open', function(){
	console.log('Connected to mongodb');
});



var app = express();

app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');
app.use(express.static(path.join(__dirname, 'public')));

app.use(bodyParser.urlencoded({expanded: false}));
app.use(bodyParser.json());

app.use(session({
	secret: 'Keyboard cat',
	resave: false,
	saveUnitialited: true,
	cookie: {secure: true}

}));

app.use(expressValidator({
	errorFormatter: function(param, msg, value){
		var namespace = param.split('.')
		, root = namespace.shift()
		, formParam = root;

		while(namespace.length){
			formParam += '[' + namespace.shift() +']';
		}

		return {
			param: formParam,
			msg: msg,
			value: value
		};

	}
}));

app.use(require('connect-flash')());
app.use(function (req, res, next){
	res.locals.messages = require('express-messages')(req, res);
	next();
});

var pages = require('./routes/pages.js');
var adminPages = require('./routes/admin_pages.js');
app.use('/admin/pages', adminPages);
app.use('/', pages);

var port = 3000;
app.listen(port, function(){
	console.log('Server started on port ' + port);
} );

index.ejs

<%- include('_layouts/header'); -%>

<h1>Hello there</h1>

<%- include('_layouts/footer'); -%>

header.ejs

<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <meta name="description" content="">
   
    <title><%= title %></title>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" integrity="sha384-Vkoo8x4CGsO3+Hhxv8T/Q5PaXtkKtu6ug5TOeNV6gBiFeWPGFN9MuhOf23Q9Ifjh" crossorigin="anonymous">

  </head>
  <body>
    <nav class="navbar navbar-expand-md navbar-dark bg-dark">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarsExampleDefault" aria-controls="navbarsExampleDefault" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>

  <div class="collapse navbar-collapse" id="navbarsExampleDefault">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li>
      <li class="nav-item">
        <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
      </li>
      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="#" id="dropdown01" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Dropdown</a>
        <div class="dropdown-menu" aria-labelledby="dropdown01">
          <a class="dropdown-item" href="#">Action</a>
          <a class="dropdown-item" href="#">Another action</a>
          <a class="dropdown-item" href="#">Something else here</a>
        </div>
      </li>
    </ul>
    <form class="form-inline my-2 my-lg-0">
      <input class="form-control mr-sm-2" type="text" placeholder="Search" aria-label="Search">
      <button class="btn btn-secondary my-2 my-sm-0" type="submit">Search</button>
    </form>
  </div>
</nav>

<main role="main" class="container">

  

<%- messages('messages', locals) %>

messages.ejs

<% Object.keys(messages).forEach(function (type) { %>

	<div class="alert alert- <%= type %>">
<%messages[type].forEach(function (message)) {%>
<%= message %>
<%}) %>
</div>
<%})%>