In case when user does not have enough permissions to view clusters ( = make a LIST action on subscription resource), ui should display an informative message to let the user know what went wrong.

Right now we display "This page is temporarily unavailable" and "Try refreshing the page. If the problem persists, contact your organization administrator or visit our status page for known outages."
This is not related to the real error (not enough permissions).

Currently, the scenario that user doesn't have permission to view any cluster is not likely to happen, but -

1. We should match cli behavior (it returns 403 access denied)
2. It may change in the future