message: ad_traverse() clearing ignore invalid edges
diff: @@ -1503,9 +1503,12 @@ void ad_traverse(bool retain_graph) {
  [](EdgeRef e1, EdgeRef e2) { return e1.target == e2.target; }),
  todo.end());
  - for (EdgeRef edge_ref : todo)
  + for (EdgeRef edge_ref : todo) {
  + if (state.variables.find(edge_ref.target) == state.variables.end())
  + continue;
  ad_free_edges(edge_ref.target, state[edge_ref.target]);
  }
  + }
  ad_log(Debug, "ad_traverse(): done.");
  