fix returned empty object and null values

jsonform/gadget_json_generated_form_child.js

@@ -1357,7 +1357,12 @@
           }
         }
         if (count_of_values === 0) {
-          return;
+          switch (g.props.type) {
+          case "object":
+            return {};
+          default:
+            return null;
+          }
         }
         return multi_level_dict[""];
       });
@@ -1566,6 +1571,7 @@
       if (!options.type && schema && !schema.type) {
         options.type = guessSchemaType(schema);
       }
+      g.props.type = options.type;
       while (root.firstChild) {
         root.removeChild(root.firstChild);
       }