message: Remove no longer needed exception check
  Since the table is fully initialized and now marked `const`, we know it
  can never be empty. Effectively the exception check was made dead code.
diff: @@ -34,9 +34,6 @@ const ProductionTypeTable PRODUCTION_TYPE_TABLE =
  const ProductionCost& productCost(ProductType _pt)
  {
  - // Sanity check
  - if (PRODUCTION_TYPE_TABLE.empty()) { throw std::runtime_error("Factory::productionCost() called before production table filled!"); }
  -
  return PRODUCTION_TYPE_TABLE.at(_pt);
  }
  