Awesome, thanks for sharing!
There’s no OOTB support for redirecting a user to Universal Login with the error message - As it stands your application will need to handle what to do next with the error params/user returned to the callback. What I have seen in this scenario is a user being presented with some sort of error page (using the error params) and an option to click to bring up universal login once more with (loginWithRedirect({prompt: ‘login’})) for example.