UITableViewDiffableDataSource não suporta nil?

No exemplo de código a seguir

import UIKit

struct Language: Hashable {
    let name: String
}

enum Section {
    case main
}

class ViewController: UIViewController, UITableViewDelegate {
    var tableView: UITableView!
    private typealias DataSource = UITableViewDiffableDataSource<Section, Language?>

    private var dataSource: DataSource!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Set up the table view
        tableView = UITableView(frame: view.bounds)
        view.addSubview(tableView)
        
        // Register a simple cell
        tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
        
        // Set up the data source
        dataSource = DataSource(tableView: tableView) { tableView, indexPath, language in
            let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
            
            // Check if the language is nil and configure the cell accordingly
            if let language = language {
                cell.textLabel?.text = language.name
            } else {
                cell.textLabel?.text = "No Language"
            }
            return cell
        }
        
        // Set up the snapshot with some sample data including nil
        var snapshot = NSDiffableDataSourceSnapshot<Section, Language?>()
        snapshot.appendSections([.main])
        snapshot.appendItems([Language(name: "English"), nil, Language(name: "Spanish"), Language(name: "French")])
        
        // Apply the snapshot to the data source
        dataSource.apply(snapshot, animatingDifferences: true)
        
        tableView.delegate = self
    }
}

Estou recebendo erro de tempo de execução

Could not cast value of type 'NSNull' (0x1ec78e900) to 'xxx.Language' (0x1008e0468).

Não é UITableViewDiffableDataSourcecompatível nil? Não consigo encontrar https://developer.apple.com/documentation/uikit/uitableviewdiffabledatasource falando sobre essa limitação.

Obrigado.