I think runtime errors are a fine way of detecting such failings. I don't understand why typing is at odds with that. I think types make us write out the why n

I think runtime errors are a fine way of detecting such failings. I don't understand why typing is at odds with that. I think types make us write out the why next to the what. That why might be a domain model justification, or something much more trivial. It's also completely possible to encode an untyped regime in a type system. You're always crystallizing your design, you just can either provide good information to understand its failings and be more prepared to fix them. Or not and chase logic errors throughout an undocumented, dynamic system.