the reply button wasn't there and I assumed the reach of a depth limit... guess I just needed to wait a bit ¯\_(ツ)_/¯

Moving the case for a default value to the caller is a weird choice IMHO. Types should reflect the assumed state about a program, but we all know the runtime can behave in unexpected ways. Assume an SPA and the response of an API call was typed with CountryCode in some field, then somebody just worked on the API - I prefer to crash my world close to were my assumption doesn't fit anymore, but YMMW.

Your implementation (and safety from the type checker) only helps at build time and puts more responsibility and care on the caller. That implementation could prolong the error throwing until undefined reaches the database, mine could already crash at the client. Either TS or JS will do that.