fix getContent for empty array

gadget_json_generated_form_child.js

@@ -1018,6 +1018,9 @@
         array = options.arrays[path]
           .querySelectorAll("div[data-gadget-parent-scope='" + g.element.getAttribute("data-gadget-scope") + "']");
         len = array.length;
+        if (len === 0) {
+          convertOnMultiLevel(multi_level_dict, path.slice(0, -1), []);
+        }
         for (i = 0; i < len; i = i + 1) {
           getContentAndPushArray(
             array[i].getAttribute('data-gadget-scope'),