Even after doing the above, carrinho will be an empty object {} as for it to be filled, the criarCarrinho() should run, but it will not run at all because of if (typeof carrinho === "undefined") in the checarCarrinhoExiste() function. This is because carrinoho will either have an {} object or whatever was saved in localstorage when the load() function runs and hence it's type will not be undefined, Hence, in addition to declaring carrinho in the global scope, change the above IF condition to if (typeof carrinho !== "undefined") and your code should work now as you intended.
Try and let us know if it works. All the best!