Hello Marco,
We have the update from our development team. This is not a bug. After first click login_service is executed, "success" event is fired and loading of second page begins, but only till executing this custom JS code:
codenavigator.notification.alert(...)/code
This is the reason of first error: "Cannot read property 'alert' of undefined"
This error interrupts loading of the second page so we still can see the first one, but a context for searching elements during mapping was changed. Thus, after the second click when login_service is executed again, "password" and "login" inputs can't be found in the new context.
ThiIs won't happen if you run installed app on device or if you use'll use a simple codealert()/code instead of codenavigator.notification.alert(...)/code.