Say, I have the following class,

class Some implements Comparable<Some> {

    @Override
    public int compareTo(Some o) {
        Objects.requireNonNull(o, "o is null");
        // Let's just compare this.other and o.other.
        // What should I do when this.other is null?
        return this.other.compareTo(o.other);
    }

    private Other other;
}

I just want to compare the this.other and o.other.

What should I do(throw) when this.other is null? Just NullPointerException or IllegalStateException?