Porque me sale este error?? &quot;Write operation failed: computed value is readonly&quot; Ayudaaa!! <code> const{ createApp, ref, reacti...

Porque me sale este error??

"Write operation failed: computed value is readonly"

Ayudaaa!!

 const{ createApp, ref, reactive, toRefs, watch, computed } = Vue;

        const app = createApp({
        setup() {
          const products = ref([
            {
              name: "Camara",
              price: 450_000,
              stock: 3,
              content: `Lorem ipsum dolor sit amet consectetur adipisicing elit. Deserunt
                atque dolorum corporis, reiciendis eaque temporibus quod magnam amet
                ea natus delectus? Aut placeat ipsam minus labore voluptas. Porro,
                vel aliquid!`,
              images: [
                {
                  image: "./img/camara.jpg",
                  thumbnail: "./img/camara-thumb.jpg"
                },
                {
                  image: "./img/camara-2.jpg",
                  thumbnail: "./img/camara-2-thumb.jpg"
                }
              ],
              offer: true,
              new: true,
              quantity: 1
            },
            {
              name: "Microfono",
              price: 950_000,
              stock: 3,
              content: `Lorem ipsum dolor sit amet consectetur adipisicing elit. Deserunt
                atque dolorum corporis, reiciendis eaque temporibus quod magnam amet
                ea natus delectus? Aut placeat ipsam minus labore voluptas. Porro,
                vel aliquid!`,
              images: [
                {
                  image: "./img/camara.jpg",
                  thumbnail: "./img/camara-thumb.jpg"
                },
                {
                  image: "./img/camara-2.jpg",
                  thumbnail: "./img/camara-2-thumb.jpg"
                }
              ],
              offer: true,
              new: true,
              quantity: 1
            },
            {
              name: "Camara PL",
              price: 250_000,
              stock: 2,
              content: `Lorem ipsum dolor sit amet consectetur adipisicing elit. Deserunt
                atque dolorum corporis, reiciendis eaque temporibus quod magnam amet
                ea natus delectus? Aut placeat ipsam minus labore voluptas. Porro,
                vel aliquid!`,
              images: [
                {
                  image: "./img/camara.jpg",
                  thumbnail: "./img/camara-thumb.jpg"
                },
                {
                  image: "./img/camara-2.jpg",
                  thumbnail: "./img/camara-2-thumb.jpg"
                }
              ],
              offer: true,
              new: true,
              quantity: 1
            },
            {
              name: "Audifonos PL",
              price: 750_000,
              stock: 5,
              content: `Lorem ipsum dolor sit amet consectetur adipisicing elit. Deserunt
                atque dolorum corporis, reiciendis eaque temporibus quod magnam amet
                ea natus delectus? Aut placeat ipsam minus labore voluptas. Porro,
                vel aliquid!`,
              images: [
                {
                  image: "./img/camara.jpg",
                  thumbnail: "./img/camara-thumb.jpg"
                },
                {
                  image: "./img/camara-2.jpg",
                  thumbnail: "./img/camara-2-thumb.jpg"
                }
              ],
              offer: true,
              new: true,
              quantity: 1
            }
          ]);

          const cartState = reactive({
            cartOpen: false,
            cart: [],
            total: computed(()=> {
              return cartState.total = cartState.cart.reduce((prev, curr) => {
              const prevPrice = prev.price || prev;
              const prevQuantity = prev.quantity || 1;
              return prevPrice * prevQuantity + curr.price * curr.quantity;
              }, 0);
            })
            /* total: 0 */
          });

          /* const total = computed(()=>{
            return cartState.total = cartState.cart.reduce((prev, curr) => {
              const prevPrice = prev.price || prev;
              const prevQuantity = prev.quantity || 1;
              return prevPrice * prevQuantity + curr.price * curr.quantity;
            }, 0);
          }) */

          function addToCart(product) {
          const prodIndex = cartState.cart.findIndex(prod => prod.name === product.name);
            if (prodIndex >= 0) {
              cartState.cart[prodIndex].quantity += 1;
            } else {
              cartState.cart.push(product);
            }
            product.stock -= 1;
          }

          /* watch(cartState.cart, (value, oldValue) => {
            cartState.total = cartState.cart.reduce((prev, curr) => {
                const prevPrice = prev.price || prev;
                const prevQuantity = prev.quantity || 1;
                return prevPrice * prevQuantity + curr.price * curr.quantity;
              }, 0);
          }) */

          return {
            ...toRefs(cartState),

            addToCart,

            products
          };
        }
      });