Ember: issue when refreshing the index page

When I refresh the index page of ember app, it appears that I can't call the functions inside my index.js file located in app/routes.

I don't really know how I can solve this issue.

The source code of inex.js:

import Ember from 'ember';
import LeosacRoute from 'web/leosac-route';

export default LeosacRoute.extend({
    authSrv: Ember.inject.service('authentication'),
    _title: 'index.title',
    _requireAuth: true,
    beforeModel()
    {
        "use strict";
        this._super();
    },
    model()
    {
        "use strict";
        console.log(this.get('authSrv').username);
        return {user_id: this.get('authSrv').user_id,
            username: this.get('authSrv').username};
    }
});

In the code source above we can see that I try to display the username. When I first log onto this page, it display well, but when I refresh the page, it doesn't display anything.
Any thought about it is welcomed!