[FIX] barcodes: nomenclature

Loads the barcode nomenclature only if one has been is defined. Indeed,
from commit 80e89c7a11, the POS config unset the
`barcode_nomenclature_id` field if the barcode support is not activated.

opw-1859928

addons/barcodes/static/src/js/barcode_parser.js

@@ -18,6 +18,9 @@ var BarcodeParser = Class.extend({
     // only when those data have been loaded
     load: function(){
         var self = this;
+        if (!this.nomenclature_id) {
+            return;
+        }
         var id = this.nomenclature_id[0];
         rpc.query({
                 model: 'barcode.nomenclature',