message: Add type dependent static_assert to ensure known type
  A static_assert with a fixed false condition will be triggered even in
  the non-instantiated branch of a constexpr-if. The solution is to make
  the false value type dependent. This delays expansion until the
  constexpr-if can eliminate branches not on the actual code path.
diff: @@ -15,6 +15,8 @@ class PopulationPool;
  struct StorableResources;
  +template <typename T> constexpr bool dependent_false = false;
  +
  template <typename StructureType>
  constexpr Structure::StructureClass structureTypeToClass() {
  if constexpr (std::is_same_v<StructureType, Agridome>) { return Structure::StructureClass::FoodProduction; }
  @@ -58,6 +60,7 @@ constexpr Structure::StructureClass structureTypeToClass() {
  else if constexpr (std::is_same_v<StructureType, UndergroundPolice>) { return Structure::StructureClass::UndergroundPolice; }
  else if constexpr (std::is_same_v<StructureType, University>) { return Structure::StructureClass::University; }
  else if constexpr (std::is_same_v<StructureType, Warehouse>) { return Structure::StructureClass::Warehouse; }
  + else { static_assert(dependent_false<StructureType>, "Unknown type"); }
  }
  