Modal Ok Button not working

Hi on a Modal i created i get this error and the Ok button ist not working anymore:

this is my code:

    showAlert(title, message) {
        let alert = this.alertCtrl.create({
          title: title,
          message: message,
          buttons: [
              text: 'OK'

not able to reproduce your error
can you try this sample in a separate app,
its working perfectly
elaborate your problem using a plunker