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

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).

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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