storage: backward compatibility on component requirements

src/entt/entity/storage.hpp

@@ -675,7 +675,7 @@ public:
      */
     template<typename... Args>
     value_type &emplace(const entity_type entt, Args &&...args) {
-        if constexpr(sizeof...(Args) != 0u && std::is_aggregate_v<value_type>) {
+        if constexpr(std::is_aggregate_v<value_type> && (sizeof...(Args) != 0u || !std::is_default_constructible_v<value_type>)) {
             const auto it = emplace_element(entt, false, Type{std::forward<Args>(args)...});
             return element_at(static_cast<size_type>(it.index()));
         } else {