Uninformative error, when trying to connect to topic which is not added to credentials

[Sheshuk]

Observed behaviour

When I tried to do snews_pt test-connection --no-firedrill without the permissions to access the topic, I get this error message

ValueError: topic snews.connection-testing does not exist on the broker, so can't subscribe

Expected behaviour

As a user I expect an error to tell about the missing access right to the topic (which is client problem), not the missing topic (which is the server problem).

Steps to reproduce

1. Create a new scimma login, and new credentials for it
2. Run hop auth add with the new credentials
3. Don't add the snews topics to the credential.
4. Run snews_pt test-connection --no-firedrill