fix diff proxy making properties inaccessible when properties on the same object where changed

js/diff.js

@@ -2,6 +2,8 @@
  * The diff proxy records all changes to the original object without changing the original object while emulating the
  * changes for access from outside. The resulting diff object can then be applied on the original. The resulting object
  * is the same as if the changes were applied directly to the original object.
+ *
+ * NOTE: When doing any changes to this, rerun the tests cases at devNotes/tests.
  */
 App.Utils.Diff = (function() {
 	const deletedSymbol = Symbol("deleted property");
@@ -64,7 +66,8 @@ App.Utils.Diff = (function() {
 						// Deep copy in case array entries get modified later
 						localDiff[key] = _.cloneDeep(original);
 					} else if (_.isObject(original)) {
-						localDiff[key] = {};
+						// TODO check if there is a way to keep the data structure valid without the need for deep clone
+						localDiff[key] = _.cloneDeep(original);
 					}
 				}
 				localDiff = localDiff[key];