update empty cart

Author: Steph Dietz

backend/functions/assembly/crud.ts

@@ -261,6 +261,7 @@ export function addToCart(cartId: string, productId: string): string {
   const cartItemId = cartId + "_" + productId;
 
   if (cart === null || cart === "") {
+    // If cart does not exist or is empty, create a new cart with the product
     const upsertResult = upsertCart(cartId, productId);
     if (upsertResult !== cartId) {
       console.log("Failed to create new cart:");
@@ -273,8 +274,10 @@ export function addToCart(cartId: string, productId: string): string {
       return quantityResult;
     }
   } else {
-    const cartItems = cart.split(",");
+    const cartItems = cart.split(",").filter((item) => item.trim() !== "");
+
     if (cartItems.includes(productId)) {
+      // If product is already in the cart, increase the quantity
       const cartItemQuantity = collections.getText(
         consts.cartItemsCollection,
         cartItemId,
@@ -297,6 +300,7 @@ export function addToCart(cartId: string, productId: string): string {
         return upsertQuantityResult.error;
       }
     } else {
+      // Add the new product to the existing cart
       const updatedCart = cart.length > 0 ? cart + "," + productId : productId;
       const upsertResult = upsertCart(cartId, updatedCart);
       if (upsertResult !== cartId) {