Overrideing Ext.data.Store methods breaks functionality.

Good day. I ran into some trouble with Ext.data.Store class. Maybe i've got wrong idea about the Class system?

I want to do pre-processing of incoming data.
There is my code :

Code:

---

    Ext.define('App.store.PagesStore', {
        extend  : 'Ext.data.Store',
        requires: ['App.model.Page'],

        config: {
            model    : 'App.model.Page',
            data        : pages,
        },

        constructor: function(config) {
            this.callParent(config);
        },

        applyData : function(data) {
            this.callParent(data);
        },
    });

---

Overriding the constructor makes Ext.StoreManager fail with lookup and overridden applyData passes only one record to the store.

Passing arguments to parent's function seems to do the trick :

Code:

---

    Ext.define('App.store.PagesStore', {
        extend  : 'Ext.data.Store',
        requires: ['App.model.Page'],

        config: {
            model    : 'App.model.Page',
            data        : pages,
        },

        constructor: function(config) {
            this.callParent(arguments);
        },
 
        applyData : function(data) {
            /* do the data manipulations */
            this.callParent(arguments);
        },
    });

---