fix: publish button (#321)

the check was about undefined, but for some reason null is in the data (see diff)

Author: freddi301

src/components/Discounts/DiscountDetailRow.tsx

@@ -46,7 +46,7 @@ const DiscountDetailRow = ({
 }: Props) => {
   const history = useHistory();
   const [canBePublished, setCanBePublished] = useState(
-    row.original.lastBucketCodeLoadStatus !== undefined
+    row.original.lastBucketCodeLoadStatus
       ? row.original.lastBucketCodeLoadStatus === BucketCodeLoadStatus.Finished
       : true
   );