I just received the Twitch Developer Forums summary mail and read this topic. Funny because i have the same issue and currently trying to fix the null reference exception in my .NET app right now. 
Maybe someone give me a hint to fix. I deserialize the json string into an own class with explicit string array for the args. How to check the array is null/nothing? Is nothing, ubound, length? Btw. I’m getting the unbanned username through API and target_user_id.