REACT: Warning: Received NaN for the `children` attribute. If this is expected, cast the value to a string

Question

I need to use a quantity for my cart, I'm learning react, but I get this warning: Warning: Received NaN for the children attribute. If this is expected, cast the value to a string.

import { createContext, useState, useContext, useEffect } from "react";

export const CartContext = createContext([]);

export const CartProvider = ({children}) => {

    const [cart, setCart] = useState([]);
    //const cantidadProductos = cart.length;


    const [cartQuantity, setCartQuantity] = useState(0);

    useEffect(() => {
        const getQuantity = () => {
            let cantidadTotalProductos = 0;
            cart.forEach((orden)=>{
                cantidadTotalProductos += Number(orden.cantidadTotalProductos);
            });
            setCartQuantity(cantidadTotalProductos);
        }
        getQuantity();
    }, [cart]);



    const addItem = (item, cantidad) => {
        const newItem = { item, cantidad };
        const itemEsta = cart.find((order) => order.item.id === item.id);

        if(itemEsta){
            const actualizarCarrito = cart.map((order) => {
                if(order.item.id === item.id){
                    return {...order, cantidad: cantidad + order.cantidad};
                }else{
                    return order;
                }
            });
            setCart(actualizarCarrito);
        }else{
            setCart((prevState) => [...prevState, newItem]);
        }
    };

    const removeItem = (id) => {
        setCart((prev) => prev.filter((element) => element.item.id !== id));
    };

    const clearAll = () => {
        setCart([]);
    };


    return (
        <CartContext.Provider value={{ cart, addItem, removeItem, clearAll, cartQuantity }}>
            {children}
        </CartContext.Provider>
    );
};

export const useCart = () => useContext(CartContext);

And then in the component:

import './Carrito.css';
import { useCart } from "../context/CartContext";

function Carrito () {

    const { cartQuantity } = useCart();
    return <div className="editarCarrito">
        <p className="carritoCantidad">{ cartQuantity }</p>
    </div>
        
}

export default Carrito;