Hey, I’m trying to create a sealed response class. 
I do not want to use nullable type for payload of the response but couldnt find a good alternative for fail scenario. 
Is there a better approach to this problem? 
Here is my code:

sealed class Response<out RESPONSE_OBJECT>(
        val payload: RESPONSE_OBJECT?,
        val errorMessage: String) {
    
    class Success<out T>(payload: T) : Response<T>(payload, errorMessage = "")
    class Fail<out T>(errorMessage: String) : Response<T>(null, errorMessage)
}