Comment by Klaster_1

> An API call, reading a file, calling less well-behaved libraries or making some system calls can all result in objects that pass compile-time checks but will cause a runtime exception or unexpected behavior.

These all boil down to implicit `as` type casting parsed boundary data into expected types. What you suggest is replacing casts with to type narrowing guards, libraries like Zod help with some of that. I think TS needs a special flag where `JSON.parse` and alike default to `unknown` and force you to type guard in runtime.