message: Remove obsolete check
  The `switch` block was removed. The new code will throw exceptions for a
  bad `Robot::Type`, so the `Robot*` can never be `nullptr`.
diff: @@ -288,10 +288,6 @@ std::map<int, Robot*> MapViewState::readRobots(NAS2D::Xml::XmlElement* element)
  static_cast<Robodigger*>(robot)->direction(static_cast<Direction>(direction));
  }
  - // Could be done in the default handler in the above switch
  - // but may be better here as an explicit statement.
  - if (!robot) { continue; }
  -
  idToRobotMap[id] = robot;
  robot->fuelCellAge(age);
  