meta: avoid resetting nodes on meta_any::emplace if not needed

src/entt/meta/meta.hpp

@@ -506,8 +506,8 @@ public:
     template<typename Type, typename... Args>
     void emplace(Args &&...args) {
         storage.emplace<Type>(std::forward<Args>(args)...);
-        node = nullptr;
-        vtable = &basic_vtable<std::remove_const_t<std::remove_reference_t<Type>>>;
+        const auto *prev = std::exchange(vtable, &basic_vtable<std::remove_const_t<std::remove_reference_t<Type>>>);
+        node = (prev == vtable) ? node : nullptr;
     }
 
     /*! @copydoc any::assign */