Launch external application from Ionic 3 code

Ionic Framework ionic-v3
1

Hi, I am creating a PWA using Ionic 3, and want to launch external installed app from my application.
I tried using lampa startapp process, https://github.com/lampaa/com.lampa.startapp

var sApp = (window as any).startApp.set({ /* params */
  "package":"com.whatsapp"
});
sApp.start(function() { /* success */
  console.log("OK");
}, function(error) { /* fail */
  console.log(error);
});

For this start function I am getting “exec proxy not found for :: startApp :: start”

Can anyone help me…?