Fix instance variable not set to null on close

openVulkanoCpp/Vulkan/Resources/ResourceManager.cpp

@@ -119,6 +119,7 @@ namespace OpenVulkano::Vulkan
 		frameResources = {};
 		memPool.Close();
 		device = nullptr;
+		INSTANCE = nullptr;
 	}
 
 	vk::CommandBuffer& ResourceManager::GetCmdBuffer() { return frameResources[currentBuffer].cmdBuffer; }