Cannot specialize non-generic type 'DefaultsKey'

[Qu000]

import SwiftyUserDefaults

// MARK: 定义key extension DefaultsKeys { /// 用户Token var RRUserToken: DefaultsKey<String?> { .init("RRUserToken", defaultValue: "") } }

就直接报错 Cannot specialize non-generic type 'DefaultsKey' 了，为啥啊....