How to fix Framework7 gives unwanted Alert message after splashscreen

I have buggfixed a Framework7 version 5.1 app, but after build the new app showed my webpage in InAppBrowser with Alert message rather than the app itself. I have googled a lot about this but no solution.

In app.js I had this:

var ref = cordova.InAppBrowser.open ('https://www.viska.se', '_blank', 'location=yes');
ref.addEventListener('loadstart', function(event) { alert(event.url); });

I understood that this line gave the Alert message. I read documentation for InAppBrowser.

I decided to attempt to close the window with my webpage:

var ref = cordova.InAppBrowser.open ('https://www.viska.se', '_blank', 'location=yes');
ref.close();

It worked and now direct after splashscreen comes the app as it previously did and inAppBrowser works as earlier for other pages.