fix: check if product is in stock

Author: freefony

src/state-indicators.service.js

@@ -75,10 +75,12 @@ class StateIndicatorsService {
 
     const getStockAmount = function (stock, product) {
       var amount = 0
-      if (stock[product].amount && typeof stock[product].amount === 'number') {
-        amount = stock[product].amount
-      } else if (typeof stock[product] === 'number' || !isNaN(parseInt(stock[product], 10))) {
-        amount = stock[product]
+      if (stock[product]) {
+        if (stock[product].amount && typeof stock[product].amount === 'number') {
+          amount = stock[product].amount
+        } else if (typeof stock[product] === 'number' || !isNaN(parseInt(stock[product], 10))) {
+          amount = stock[product]
+        }
       }
       return amount
     }