a conceptual quick fix for #269

src/json.hpp.re2c

@@ -9312,13 +9312,16 @@ class basic_json
                     // in a second pass, traverse the remaining elements
 
                     // remove my remaining elements
+                    const auto end_index = static_cast<difference_type>(result.size());
                     while (i < source.size())
                     {
-                        result.push_back(object(
+                        // add operations in reverse order to avoid invalid
+                        // indices
+                        result.insert(result.begin() + end_index,
                         {
                             {"op", "remove"},
                             {"path", path + "/" + std::to_string(i)}
-                        }));
+                        });
                         ++i;
                     }