Address PR #825 review round 2:
- _validate_nextcloud_credentials now only maps OCS HTTP 401/403 to a 401
"invalid credential"; any other non-200 (5xx, 503 maintenance mode) surfaces
as 502 "Nextcloud returned a server error" so ops don't chase a phantom bad
password when Nextcloud is actually down.
- The client-facing 401 message is now a parameter, so delete_app_password keeps
its "Invalid credentials" wording without unwrapping/rebuilding the helper's
JSONResponse.
- Body parsing catches (ValueError, UnicodeDecodeError) instead of bare
Exception, and guards body.get behind isinstance(body, dict) — no longer
swallows RuntimeError/AttributeError or a non-object JSON body.
- Add a unit test asserting 500/503 -> 502.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
