Could you give me some tips to the crash `*** Collection <__NSCFSet: 0x28355f810> was mutated while being enumerated.`

[Insfgg99x]

the code is:

    func conversation(whereChatId: String) -> Conversation? {
        guard AERecord.Context.default.persistentStoreCoordinator != nil else {
            return nil
        }
        let predicate = NSPredicate.init(format: "chatId=%@", whereChatId)
        let con = Conversation.first(with: predicate)
        return con
    }

the crash is:

*** Collection <__NSCFSet: 0x28355f810> was mutated while being enumerated.
ClouderWork + 8451948

I have got this error some times in my project using AERecord, would you please help me to fix it? I can't fix it by myself, I need your help! Very thanks!