问基于pushViewController的CollectionView生成SIGABRT

EN

func showChatView(message: ChatMessage) {
        DispatchQueue.main.async {
            if self.chatViewController == nil  {
                let mainStoryboard : UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
                self.chatViewController = mainStoryboard.instantiateViewController(withIdentifier: "VAChatViewController") as? VAChatViewController
                self.chatViewController?.delegate = self;
            }
            self.chatViewController?.messages += [message]

            self.navigationController?.pushViewController(self.chatViewController!, animated: true, completion: {
                let buttonMessage = self.chatViewController?.messages.last
                let hasButtons = buttonMessage?.hasButtons
                if hasButtons! {
                    let vaButtonModel = ChatMessage(buttons: buttonMessage?.buttons)
                    self.chatViewController?.addNewMessage(vaButtonModel)
                }
            })
        }
    }