react-native 突然出現(xiàn)這個錯誤 不知道是為啥 之前都好好的

問題如圖 有誰知道為什么嗎？
我的代碼這樣寫的：

    ChatMessage = (item) => {
        const { navigate } = this.props.navigation;
        item['chattype'] = 'Friends'
        navigate('ChatMessage', item);
    }

Unhandled JS Exception: TypeError: One of the sources for assign has an enumerable key on the prototype chain. Are you trying to assign a prototype property? We don't allow it, as this is an edge case that we do not support. This error is a performance optimization and not spec compliant.