message: Prevent undefined behaviour when serializing robots to Xml
  Using an iterator within an empty std::map leads to undefined behaviour as caught by Visual Studio when running code in debug mode. Reference
diff: @@ -516,6 +516,10 @@ void checkRobotDeployment(XmlElement* _ti, RobotTileTable& _rm, Robot* _r, Robot
  _ti->attribute("age", _r->fuelCellAge());
  _ti->attribute("production", _r->turnsToCompleteTask());
  + if (_rm.empty()) {
  + return;
  + }
  +
  const auto it = _rm.find(_r);
  if (it->first == _r)
  {
  @@ -525,7 +529,6 @@ void checkRobotDeployment(XmlElement* _ti, RobotTileTable& _rm, Robot* _r, Robot
  _ti->attribute("y", position.y);
  _ti->attribute("depth", tile.depth());
  }
  -
  }
  