Ionic 2 error not showing in nav.push(somePage);

Ionic Framework ionic-v3
7

Change it for

goToPage4() {
    this.nav.push(Page4).then(
      response => {
        console.log('Response ' + response);
      },
      error => {
        console.log('Error: ' + error);
      }
    ).catch(exception => {
      console.log('Exception ' + exception);
    });;
  }

nothing gets executed