fix(product-listing): Check if customer exists (#24030)

- It might happen that perty_name might not always be Customer
(it might be Supplier as well)

erpnext/shopping_cart/cart.py

@@ -345,7 +345,7 @@ def _set_price_list(cart_settings, quotation=None):
 	selling_price_list = None
 
 	# check if default customer price list exists
-	if party_name:
+	if party_name and frappe.db.exists("Customer", party_name):
 		selling_price_list = get_default_price_list(frappe.get_doc("Customer", party_name))
 
 	# check default price list in shopping cart