I've read elsewhere that one idea for the zero value of sum types is not making it nillable, but rather making the zero value as the 0th variant of the sum type (and if it has associated data, the zero value of that as well).

It's weird, but does align with design decisions that have already been made.

So if there was an `Option[T]` with variants `None` and `Some[T]`, the zero value would be `None` because that's the zero-th variant