Detect when user cancels authentication

[michaeltintiuc]

It is possible for the user to close the popup window and not authenticate, this results in a failed login attempt without any means to catch it.

The workaround that I have found is to set an interval and watch the windowHandle.close of OAuth2Client class, but this property is not public meaning that in TypeScript I have to extend the interface.

It's quite a bit of extra work and could easily be part of the source.

[moberwasserlechner]

Could you share your code in a PR please?

[michaeltintiuc]

Note that I have to do 2 things to make it work with TypeScript properly:

1. Plugins.OAuth2Client is declared option, thus I get warning that OAuth2Client could be udnefined
2. Plugins.OAuth2Client as any so that I could silence the warning of windowHandle not existing

          const timer = setInterval(function() {
            if ((Plugins!.OAuth2Client as any).windowHandle.closed) {
              clearInterval(timer);
              handleAuthError();
            }
          }, 500);

          const authResult = await Plugins!.OAuth2Client!.authenticate(data);

[moberwasserlechner]

If the user cancels the login process by closing the windows the error code "USER_CANCELLED" will be returned.

This functionality and error is already present for iOS and Android.