Accessing the parsed authority (via urlparse/.hostname) raises ValueError
on a malformed bracketed host, e.g. https://[not-an-ip]/..., mirroring
the existing .port guard below. download_url is server-controlled (a
catalog download_url payload), so the function's resolve-or-return-None
contract must hold rather than leaking a raw traceback to the caller.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>