The current Optional.construct returns nil when the given JS value is null or undefined, but nilmeans a failure during decode here, so it's semantically wrong. Instead, it should return.some(nil)`.

Also, when Wrapped.construct returns nil, it means decode operation failed, so Optional.construct method should return nil. But it might be unclear that the returned Optional<Wrapped> value won't be implicitly casted to .some(nil), so I changed to return nil by guard statement explicitly.