message: return if other agent is not found as well
diff: @@ -115,6 +115,8 @@ inline void ComputeSafetyPolygon(
  if (directional == LonDirectionMode::AUTO) {
  // calculate if the agent is in front or behind
  auto other_agent = observed_world.GetAgents()[safe_poly.agent_id];
  + if (!other_agent)
  + return;
  auto other_pose = other_agent->GetCurrentPosition();
  double relative_angle = atan2(
  bg::get<1>(ego_pose) - bg::get<1>(other_pose),
  