Merge instead of assign, maybe?

js/utils.js

@@ -365,7 +365,7 @@ function sortArrayByArray(sorted, unsorted, key) {
  * @param {object} source
  */
 function deepAssign(target, source) {
-	_.assign(target, _.cloneDeep(source));
+	_.merge(target, _.cloneDeep(source));
 }
 
 /**