Function nullableFromUnion

src/Type.ts:405–410

(t: UnionType)

}

export function nullableFromUnion(t: UnionType): Type | null {
    const [hasNull, nonNulls] = removeNullFromUnion(t);
    if (!hasNull) return null;
    if (nonNulls.size !== 1) return null;
    return defined(nonNulls.first());
}

export function nonNullTypeCases(t: Type): OrderedSet<Type> {
    if (t.kind === "null") {