Minor refactor to parsing and testing cleanup

src/utility.c

@@ -116,7 +116,7 @@ struct ucl_object *ucl_list_append(struct ucl_object *list, struct ucl_object *o
 
     if (list->cell.car == NULL) {
         list->cell.car = obj;
-        return list;
+        return NULL;
     }
 
     while (iter->cell.cdr != NULL) {
@@ -124,7 +124,7 @@ struct ucl_object *ucl_list_append(struct ucl_object *list, struct ucl_object *o
     }
     iter->cell.cdr = ucl_cell_create(obj, NULL);
 
-    return list;
+    return iter->cell.cdr;
 }
 
 void ucl_print_obj(struct ucl_object *obj) {