createMutable function and getters issue

[teddybee]

I saw in a tutorial, that createMutable objects can have its own logic. That would be good in simpler scenarios, I can use those objects as a global state management solution. Unfortunately, it works very hectic. For example there is a cart object, I can push products into the products, but I cant reset/clear the array, because it is undefined. I experienced some undefined issue also, when I want to use getters inside another inner function. Am I doing wrong or this is a bug in the latest versions?
My cart createMutable look like this:

export const cart = createMutable({
  products: [] as Product[],

  get total() {
    return this.products.reduce((total, product) => total + product.price, 0);
  },


  get isEmpty() {
    return this.products.length === 0;
  },

  addToCart(product: Product) {    
    this.products.push(product);    
    console.log(this.total); //this.total is working
  },

  clearCart() {   
    if (this.products) { //always undefined somehow
      console.log("clear");
      this.products = [] as Product[],  
    } else {
      console.log("this.products is undefined");
    }
  },

  checkout() {
    console.log(this.total);

    if (!this.isEmpty) { //also undefined     
      window.alert(`You have just checked out products`);     
    }
  },
});

[teddybee]

Ahh, it was my fault. I called the method from button like this accidentally:
cart.clearCart without parenthesis.
<button onclick={()=> cart.checkout()}> has fixed the issues.