Open two Alert at the same time

Hello,
I’m using ionic beta 11 and I need to open two or more alert at the same time. This because there could be one or more errors in some functions but when the second alert is created the app stops working.
For example I put this code in the constructor but It seems to open one Alert and when I close it the UI doesn’t work anymore.

this.alertController.create({
    title: 'Alert 1',
    subTitle: 'text 1',
    buttons: ['Dismiss']
  }).present();
this.alertController.create({
    title: 'Alert 2',
    subTitle: 'text 2',
    buttons: ['Dismiss']
  }).present();

Can you help me?

Thanks,
Stefano