Listing programs of a particular type in a nonexistent namespace returns 200
Make an HTTP request to get the services in a nonexistent namespace:
It will return 200, with an empty list.
Same issue is there for other program types.
Instead, it should return with a 404, because the namespace doesn't exist.
Listing the programs in a non-existent namespace now returns 404 instead of the 200 it was returning previously.