Yeah, that example is unsound in the same way that Java's type system is unsound, it's a compromise nearly all languages make to avoid forcing you to add checks

Yeah, that example is unsound in the same way that Java's type system is unsound, it's a compromise nearly all languages make to avoid forcing you to add checks when you know what you're doing. That's not the kind of problem that people usually are referring to when they single out TypeScript.