If you mean type aliases, that's a good idea within a single codebase, but the distinction between different types of strings doesn't survive serialization so it wouldn't have prevented this error. What they need is a way to signal errors out-of-band, like Result<T> or exceptions.

This is presuming that the type system is nomitive rather than structural and there is not serialisation/deserialisation or type refinement occurring. A structural difference is much more preferable.