CreateEntity should be nodiscard

headers/Containers/DualkeyMap.hpp

@@ -200,8 +200,8 @@ private:
           firstKey(std::move(firstKey)), secondKey(std::move(secondKey)),
           value(std::move(value)) {}
 
-    std::size_t firstKeyHash = 0;
-    std::size_t secondKeyHash = 0;
+    const std::size_t firstKeyHash;
+    const std::size_t secondKeyHash;
     const AKey firstKey;
     const BKey secondKey;
     mutable Value value;

headers/Systems/ECS.hpp

@@ -40,6 +40,7 @@ concept Component = std::derived_from<T, BaseComponent>;
 class World {
 public:
   // Entity
+  [[nodiscard]]
   Entity CreateEntity();
   bool EntityExists(const Entity &entity) noexcept;
   [[nodiscard("It is not guaranteed that an entity can always be destroyed, "