Actually, a number of modern languages have addressed this. A few of them are: Dart, Rust, and Vlang. However, many of the newer languages seem to address or handle null (nil) safety, a bit differently from each other.

In Dart[1] and Vlang[2], for example, "non-nullable" is the default. Vlang doesn't allow null or nil to be used, unless code is marked as unsafe, and primarily only for compatibility with languages that do (like C). In Dart, nullable variables have `?` added to the end of them.

[1]: https://en.wikipedia.org/wiki/Dart_(programming_language)

[2]: https://en.wikipedia.org/wiki/V_(programming_language)