Time for action – checking negative scene indexes

Let's keep things simple on our first foray into exceptions and make sure that our level only restarts if we provide a positive scene index number:

1. Open up Utilities and add in the following code to the overloaded version of RestartLevel():

public static class Utilities 
 {
     public static int playerDeaths = 0;
 
     public static string UpdateDeathCount(out int countReference)
     {
         // ... No changes needed ...
     }
 
     public static void RestartLevel()
     {
         // ... No changes needed ...
     }
 
     public static bool RestartLevel(int sceneIndex) 
     {
         // 1
         if(sceneIndex < 0)
         {
             // 2
             throw new System.ArgumentException("Scene index cannot
                 be negative");
         }
 
         SceneManager.LoadScene(sceneIndex);
         Time.timeScale = 1.0f;
 
         return true;
     }
 }

2. Change RestartLevel() in the OnGUI() method...