The "mistake" was not in providing a way to represent "no data", it was in providing no way to represent "this definitely HAS" data.

Languages that correct the problem have two separate types (eg: Foo & Option<Foo>) meaning "definitely a Foo" and "a Foo but it might have no data". Java just has Foo, meaning "a Foo but it might have no data" but no way to represent "definitely a Foo".