Spec reviewer caught a systemic gap during Task 6 (navigation) review:
Plan 8 left every feature's domain error class with a constructor that
didn't set this.name = '<ClassName>'. Plan 9 spec R6 requires it.
Fixed across all 10 error files:
- auth: AuthenticationError, UnauthenticatedError, UnauthorizedError, InputParseError
- blog: ArticleNotFoundError, InputParseError
- marketing-pages: PageNotFoundError, InputParseError
- navigation: HeaderNotFoundError, InputParseError
- media: MediaNotFoundError, InputParseError
Functionally a no-op — defineErrorMiddleware uses instanceof, not name —
but ensures correct serialization, stack traces, and JSON inspection.
Refactor log: §7
Spec: R6