vue3写的。

  const methods = {

      addCart() {
        addProductCart({
          productId: productId.value,
          selected: true,
        }).then((res = 0) => {
          $store.dispatch("saveCartCount", res);
          $router.push('/cart')
        })

      }
    }
    onMounted(() => {
      productId.value = $route.params.id;
      getProductInfo(productId.value).then((res) => {
        productInfo.value = res;
      });
    })
    return {
      ...methods,

$http.interceptors.response.use(
  (response) => {
    let res = response.data;
    if (res.status == 0) {
      return res.data;
    } else if (res.status == 10) {
      if (location.hash != "#/index") {
        window.location.href = "/#/login";
      }
      return Promise.reject(res.msg);
    } else {
      return Promise.reject(res);
    }
  },
  (error) => {
    return Promise.reject(error);
  }
);

报错：

runtime-core.esm-bundler.js?5c40:218 Uncaught TypeError: Cannot read properties of undefined (reading 'then')
    at Proxy.addCart (Detail.vue?d0d1:143:1)
    at Object.onClick._cache.<computed>._cache.<computed> (Detail.vue?d0d1:64:1)
    at callWithErrorHandling (runtime-core.esm-bundler.js?5c40:155:1)
    at callWithAsyncErrorHandling (runtime-core.esm-bundler.js?5c40:164:1)
    at HTMLAnchorElement.invoker (runtime-dom.esm-bundler.js?830f:369:1)
addCart @ Detail.vue?d0d1:143
Object.onClick._cache.<computed>._cache.<computed> @ Detail.vue?d0d1:64
callWithErrorHandling @ runtime-core.esm-bundler.js?5c40:155
callWithAsyncErrorHandling @ runtime-core.esm-bundler.js?5c40:164
invoker @ runtime-dom.esm-bundler.js?830f:369
:8080/#/login:1 Uncaught (in promise) NEED_LOGIN