Hi, there.

I am studying a example: binding-child-session.

When I try to save the form I get the error:

Uncaught TypeError: Cannot read property 'getItems' of null

Code:
...
onSaveClick: function() {

        var me = this,
            form = me.lookupReference('formPhones');


        if (form.isValid()) {
            form.submit({
                clientValidation: true
                , url: 'foo.php'
                , scope: me
                , success: 'onSaveSuccess'
                , failure: 'onSaveFailure'
            });
        }
        // Save the changes pending in the dialog's child session back to the
        // parent session.
        this.dialog.getSession().save();


        this.onCancelClick();
    },
...
Code:
...
Ext.define('KitchenSink.view.binding.ChildSessionForm', {    extend: 'Ext.window.Window',
    xtype: 'binding-child-session-form',


    bind: {
        title: 'Edit {theCustomer.name}'
    },
    layout: 'fit',
    modal: true,
    width: 400,
    height: 350,
    closable: true,


    items: {
        xtype: 'form',
        reference: 'formPhones',
        bodyPadding: 10,
        border: false,
        items: [{....
Fiddle: https://fiddle.sencha.com/#view/editor&fiddle/228s

Is there a clever way to save the form? I am a beginner..

thanks