How to show SignIn Widget Authentication Error

I am currently using the Okta SignIn widget for a SPA to have users login and redirect back to our App. The widget seems to be mostly working, access and ID tokens are being sent back with a successful login and redirect. When a user who is not assigned to the app tries to log in, they still redirect, but are not given a token, and the access denied error is fed back through the URL (“access_denied&error_description=User+is+not+assigned+to+the+client+application.”). After getting a few questions answered by support, it would appear that this is intended behavior, and it is up to us to handle the information and deny the login.

I have been looking through the SignIn widget Github, and it looks like this authentication failure should be pushed back and displayed on the widget (see below).

 function error(err) {
// The widget will handle most types of errors - for example, if the user
// enters an invalid password or there are issues authenticating.
// This function is invoked with errors the widget cannot recover from:
// 2. Uncaught exceptions

Note : This question is raised by other user, I have reposted it as i am facing same issue

Have you tried to go with this path?