使用EXT4报错！大神快来看~求解决

Ext.application({
    name:'AM',
    appFolder:'js',
    controllers:["Users"],
    launch: function () {
        Ext.create('Ext.container.Viewport', {
            layout: 'fit',
            items: [{
                xtype: 'userlist'
            }]
        });
     }
});

Ext.define('AM.controller.Users', {
    extend: 'Ext.app.Controller',
    views: [
        'List',
        'Edit'
    ],
    stores:[
        "Users"
    ],
    models:["User"],
    init: function () {
        this.control({
            'userlist': {
                itemdblclick: this.editUser
            }
        });
    },
    editUser: function(grid, record) {
        console.log('Double clicked on ' + record.get('name'));
    }
});

Ext.define('AM.model.User', {
    extend: 'Ext.data.Model',
    fields: ['name', 'email']
})

Ext.define('AM.store.Users', {
    extend: 'Ext.data.Store',
    model: 'AM.model.User',
    data: [
        { name: 'Ed', email: 'ed@sencha.com' },
        { name: 'Tommy', email: 'tommy@sencha.com' }
    ]
});

Ext.define('AM.view.List', {
    extend: 'Ext.grid.Panel',
    alias: 'widget.userlist',
    title: 'All Users',
    initComponent: function () {
        this.store = "Users";
        this.columns = [
            { header: 'Name', dataIndex: 'name', flex: 1 },
            { header: 'Email', dataIndex: 'email', flex: 1 }
        ];
        this.callParent(arguments);
    }
});