Object reference not set to an instance of an object.
   at ZombieBlocks.NetworkedGameplayScreen.Unload()
   at GameStateManagement.ScreenManager.UnloadContent()
   at Microsoft.Xna.Framework.DrawableGameComponent.Dispose(Boolean disposing)
   at Microsoft.Xna.Framework.GameComponent.Dispose()
   at Microsoft.Xna.Framework.Game.Dispose(Boolean disposing)
   at Microsoft.Xna.Framework.Game.Dispose()
   at ZombieBlocks.Program.Main(String[] args)