Import repositories page won't show any error if the connection to api url of external services Bitbucket Cloud not allowed

Summary

Import repositories page won't show any error if the connection to api url of external services like Bitbucket Cloud is blocked by proxy or firewall. It appears that initial connection is successful but HttpRequestFailedEvent is not handled in UI

Environment

outbound proxies or firewalls configured to block certain external connections

Steps to Reproduce

Configure outbound proxy to block connection attempt to api URL of BItbucket cloud  https://api.bitbucket.org

Expected Results

Successfully list the repositories after the "Connect" button is clicked.

Actual Results

When clicking on the 'connect' button, nothing happens. It just gets grayed out and stays on the page unless interrupted.

POST /rest/importer/latest/external-source/missing-oauth-scopes HTTP/1.1" c.a.b.i.i.r.ExternalRepositoryResource Error making external request: Request forbidden 

Workaround

Allow connection through outbound proxy or firewall