why it doesn't work in this situation

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

let storage = try? Storage(
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)
}
}