ExtJS 4.1: “Uncaught TypeError: Cannot call method 'substring' of undefined”

I was getting the error :

“Uncaught TypeError: Cannot call method 'substring' of undefined”

When I was trying to initialize an object from this class definition:


Ext.define('WebMonitorClass.view.CrearBodegaFormPanel', {    
    extend: 'Ext.form.FormPanel'
    ,alias: 'widget.crearBodegaFormPanel'       
    ,layout:'absolute'
    ,border:false
    ,padding : '0 0 5 0'
    ,bodyStyle:'background-color: #DFE9F6;'
    ,width:360
    ,height:110
    ,initComponent: function() {                                                    
        this.callParent();                                    
    }
    ,items:[
        {xtype: 'bodegaDatosBasicosFieldSet'}
    ]
    ,buttonAlign:"center"
    ,buttons:[]
});

the solution was adding the require config parameter importing the file which that contains the definition of the bodegaDatosBasicosFieldSet class:

,requires: [ 'WebMonitorClass.view.BodegaDatosBasicosFieldSet' ]

So, the resulting class definition was


Ext.define('WebMonitorClass.view.CrearBodegaFormPanel', {    
    extend: 'Ext.form.FormPanel'
    ,requires: [ 'WebMonitorClass.view.BodegaDatosBasicosFieldSet' ] // here is what I added
    ,alias: 'widget.crearBodegaFormPanel'       
    ,layout:'absolute'
    ,border:false
    ,padding : '0 0 5 0'
    ,bodyStyle:'background-color: #DFE9F6;'
    ,width:360
    ,height:110
    ,initComponent: function() {                                                    
        this.callParent();                                    
    }
    ,items:[
        {xtype: 'bodegaDatosBasicosFieldSet'}
    ]
    ,buttonAlign:"center"
    ,buttons:[]
});