Custom connection to Trello (OAuth) - Error when user selects 'Deny' on Trello authorization

Hi,
I have integrated Trello using a Custom Connection (OAuth) and the process works fine and my app callback gets called OK when I select ‘Authorize’ on the Trello authorization page. However if I select ‘Deny’ I get an auth0 Opps page - URL and Text below. (Client app is Auerlia SPA with auth0-js).

https://lintfreelogic.au.auth0.com/login/callback#token=

You may have pressed the back button, refreshed during login, opened too many login dialogs, or there is some issue with cookies, since we couldn’t find your session. Try logging in again from the application and if the problem persists please contact the administrator.

What do I need to do to be able to handle this issue?

OK. Trying to use a Custom Error page and then suggest that they try again make sure they click 'Authorize on Trello page.
Note: For my testing /devi need a custom error page of http://localhost:9000/error. The Dashboard would not let me enter such a URL. However using the Management Api for Tennant settings did. See Customize Error Pages