Unreal Engine – spawning actor from content browser

What is best way to spawn Actor from UFactory ?

I am trying to create custom asset based on AActor:

UObject * UMyActorAssetFactory::FactoryCreateNew(UClass * InClass, UObject * InParent, FName InName, EObjectFlags Flags, UObject * Context, FFeedbackContext * Warn)
    return NewObject<AMyActorAsset>(InParent, InClass, InName, Flags);

Now I can create MyActorAsset. But when I try to open it, it fails because of missing world.

Is there any way to access editor world, or do I need to create new instance of world and supply that one?