Validate route IDs in metadata loaders as well as page renderers

In Next.js, validating a route identifier only in the page renderer does not protect generateMetadata or its database loaders. Validate the same input before every metadata lookup against a PostgreSQL UUID column and return appropriate fallback metadata for malformed values. Otherwise the page can select its invalid-link state while an independent metadata query throws, producing a render failure instead. Verify both metadata and page behavior together. This diagnosis applies to malformed identifiers; it does not establish failures for valid records or explain who originated the requests.

Applies when: Next.js page rendering and metadata independently consume an untrusted route identifier. Keywords: Next.js generateMetadata PostgreSQL UUID validation malformed route render failure