When the voice-limit guard (or any JWT service) answers 403 with a reason —
"This voice channel is full.", "You don't have permission to …" — EC wrapped it
in FailToGetOpenIdToken and the user saw the generic error page with
OPEN_ID_ERROR. A 403 MatrixError with a non-empty `error` now throws
SFUTokenRefusedError ("Can't join this call" + the server's sentence), so the
reason is the description. Other failures are unchanged. Unit-tested.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA