Some kind of testing is needed if you care at all about it being reliable, whether or not you have type checks. It can just be a few simple tests like a smoke.

Some kind of testing is needed if you care at all about it being reliable, whether or not you have type checks. It can just be a few simple tests like a smoke. You don't need tests that directly check for correct types. If you're using a wrong type somewhere, it'll become obvious. Without type checks, I've never had a bug in prod caused by wrong types, it's always something else.