message: Add exception checks to ensure icon size and spacing is positive
diff: #include <NAS2D/MathUtils.h>
  #include <algorithm>
  +#include <stdexcept>
  +#include <string>
  using namespace NAS2D;
  @@ -65,6 +67,11 @@ void IconGrid::sheetPath(const std::string& filePath)
  */
  void IconGrid::iconSize(int newSize)
  {
  + if (newSize <= 0)
  + {
  + throw std::runtime_error("IconGrid::iconSize must be positive: " + std::to_string(newSize));
  + }
  +
  mIconSize = newSize;
  updateGrid();
  }
  @@ -75,6 +82,11 @@ void IconGrid::iconSize(int newSize)
  */
  void IconGrid::iconMargin(int newMargin)
  {
  + if (newMargin < 0)
  + {
  + throw std::runtime_error("IconGrid::iconMargin must be non-negative: " + std::to_string(newMargin));
  + }
  +
  mIconMargin = newMargin;
  updateGrid();
  }
  