TypeError：无法读取Reactjs中未定义的属性“ 0”添加到购物车功能

Question

我有一个AddtoCart功能，在将产品添加到购物车时，单击时引发未定义的错误。

该函数index.js中的错误

componentWillUpdate(nextProps, nextState) {
if (nextState.cartPopup && nextProps.reducerKeyProductCartPage !== this.props.reducerKeyProductCartPage && nextProps.reducerKeyProductCartPage) {
            if (nextProps.reducerKeyProductCartPage.status && nextProps.reducerKeyProductCartPage.status[0].toLowerCase().includes("error")) {
                this.notify(nextProps.reducerKeyProductCartPage.message[0]);
            }
            else {
                this.notify(nextProps.reducerKeyProductCartPage.message[0], "success");
            }
            this.setState({ cartPopup: false });
        }
}

以下是“添加到购物车”功能：

addToCart = (data) => {
        this.setState({ cartPopup: true, deleteCart: false });
        let customerId = cookie.load("customerId") ? cookie.load("customerId") : 0;
        let getUrl = '';
        let stateProductData = {}
        if (customerId) {
            getUrl = constant.BaseUrl + this.state.languageValue + "-" + this.state.storeValue + "/rest/V1/customer/addtocart";
            stateProductData = { "customer_id": customerId, "lang": this.state.languageValue + "_" + this.state.storeValue, "product_id": data, "quantity": 1 }
        }
        else {
            getUrl = constant.BaseUrl + this.state.languageValue + "-" + this.state.storeValue + "/rest/V1/customer/guestaddtocart";
            stateProductData = { "quote_id": cookie.load("cartValue"), "lang": this.state.languageValue + "_" + this.state.storeValue, "product_id": data, "quantity": 1 }

        }
        this.props.commonGateway({
            reqData: stateProductData,
            url: getUrl, method: 'POST',
            resource: "cartProduct", reducerKey: "reducerKeyProductCartPage"
        });
        this.props.commonGatewayRequestDone({ reducerKey: "reducerKeyProductCartStatus" });
    }

以下是渲染方法，该方法具有添加到其他组件中的购物车按钮：

return (
<div>
<MainContainer block={idx + 2} fetchData={this.fetchData} data={this.props["reducerKeyFetchLandingPage" + (idx + 2)] ? this.props["reducerKeyFetchLandingPage" + (idx + 2)] : ""} addToCart={this.addToCart} addToWishList={this.addToWishList} rtl={this.state.languageValue} />
</div>
);

错误

的屏幕截图