ionic tab navigation bug

page1.html

<ion-navbar *navbar>
  <ion-title>Tab 1</ion-title>
</ion-navbar>

<ion-content padding class="page1">
  <h2 (click)="clicked()">Welcome to Ionic!</h2>
  <p>
    This starter project comes with simple tabs-based layout for apps
    that are going to primarily use a Tabbed UI.
  </p>
  <p>
    Take a look at the <code>www/app/</code> directory to add or change tabs,
    update any existing page or create new pages.
  </p>
</ion-content>

page1.js

import {Page, NavController} from 'ionic-angular';
import {Page2} from '../page2/page2';


@Page({
  templateUrl: 'build/pages/page1/page1.html'
})
export class Page1 {
    static get parameters() {
        return [[NavController]];
    }

    constructor(nav) {
        this.nav = nav;
    }

    clicked() {
        console.log('clicked');
        this.nav.push(Page2);
    }
}