Problems "Ext.Loader"

Good afternoon, trying to give the path to the "ux" folder to work with the "ClearButton.js" class, I see this error:

"Uncaught Error: The following classes are not declared even if their files have been loaded: 'Ext.app.Application'. Please check the source code of their corresponding files for possible typos: './app/Application.js"

Code:

// @require @packageOverrides
Ext.Loader.setConfig({
    enabled: true,
    paths: {
        Ext: '.',
        'Ext.ux': 'ux'
    }
});


Ext.application({


    requires: [
        'Ext.Loader'
    ],
    views: [
        'MyPanel'
    ],
    name: 'MyApp',


    launch: function() {
        Ext.create('MyApp.view.MyPanel', {renderTo: Ext.getBody()});
    }


});

Any advice please, thank you very much.

Sencha Architect