app: fixed error when looking for non existing parent

js/erp5_loader.js

@@ -3169,7 +3169,7 @@
           }
           // handle select > span!
           if (element.tagName === "OPTION") {
-            if (element.selected) {
+            if (element.selected && element.parentNode.previousSibling) {
               element.parentNode.previousSibling.textContent =
                 element.textContent;
             }