why it doesn't work in this situation

[ihoudf]

let diskConfig = DiskConfig(name: "Floppy")
let memoryConfig = MemoryConfig(expiry: .never)

    let storage = try? Storage<String, Data>(
        diskConfig: diskConfig,
        memoryConfig: memoryConfig,
        fileManager: FileManager.default,
        transformer: TransformerFactory.forData()
    )
    
    let user2 = User(firstName: "J222ohdsdsdn", lastName: "Sdsdsdsdnow")
    
    let customStorage = storage?.transformCodable(ofType: User.self)
    customStorage?.async.setObject(user2, forKey: "cityfd") { result in
        let ddfs = try? storage?.object(forKey: "cityfd")
        print(ddfs)
        switch result {
        case .success():
            print("saved successfully")
        case .failure(let error):
            print(error.localizedDescription)
        }
    }