message: Remove no longer useful check
  When reading a specific attribute and getting back a string, a default
  value of "" is used if the attribute isn't found. That is a safe value
  that effectively does nothing in `readRccRobots`.
diff: @@ -500,13 +500,10 @@ void MapViewState::readStructures(Xml::XmlElement* element)
  if (robotsElement)
  {
  const auto robotIds = robotsElement->attribute("robots");
  - if (robotIds != "")
  - {
  auto& robotCommand = *static_cast<RobotCommand*>(&structure);
  readRccRobots(robotIds, robotCommand, mRobotPool);
  }
  }
  - }
  if (structure.hasCrime())
  {
  