App is run forever

Did you open an app because it needs to be opened once to register your app to onesignal.
If you did then
add this function after this.oneSignal.startInit('5d4fd62b-b9f8-4e41-9a89-7ea3b18af3de','470761651487');
line

this.oneSignal.getIds().then((ids)=>{
        alert(ids.userId);
      }).catch((e)=>{
        alert(e);
      })

and let me know what did you get.