fixing error handling

shared/api/errors/codes/cusProductErrCodes.ts

@@ -0,0 +1,4 @@
+export const CusProductErrorCode = {
+	CustomerProductNotFound: "customer_product_not_found",
+	CustomerProductAlreadyExists: "customer_product_already_exists",
+} as const;

shared/api/errors/codes/productErrCodes.ts

@@ -0,0 +1,11 @@
+/**
+ * Product-related error codes
+ */
+export const ProductErrorCode = {
+	ProductNotFound: "product_not_found",
+	ProductAlreadyExists: "product_already_exists",
+	InvalidProductItem: "invalid_product_item",
+} as const;
+
+export type ProductErrorCode =
+	(typeof ProductErrorCode)[keyof typeof ProductErrorCode];