error thrown by unity about null reference exception

The error states that my object reference is not set to the instance of an object. The error is thrown in this section of my code.

Code (CSharp):

1.     public void MainMenuKey()
2.     {
3.         if (Input.GetKey(KeyCode.Return))
4.         {
5.             SceneManager.LoadScene(0);
6.         }
7.         else if (Input.GetKey(KeyCode.Backspace))
8.         {
9.             SceneManager.LoadScene(0);
10.         }
11. // LINE THROWING ERROR
12.         FindObjectOfType<GameSession>().resetScore();
13.     }

The method is held in another script and is very simple:

Code (CSharp):

1.     public void resetScore()
2.     {
3.         Destroy(gameObject);
4.     }

I don't understand why its throwing this error code. Should I just write to destroy the game object at the end of my other code instead of calling the method from the other script?

 

What is the exact error message? Please, quote it.

In general Find* function in Unity are a poor idea and always can and should be replaced by direct object access - see
https://starmanta.gitbooks.io/unitytipsredux/content/first-question.html

 

It would help if you showed the actual error message, but my guess would be that FindObjectOfType<GameSession>() returns null, thus null.resetScore() throws the exception. Does an object with a script of type GameSession attached exist in your scene hierarchy?

 

The exact error is:

NullReferenceException: Object reference not set to an instance of an object
PlayAgain.MainMenuKey () (at Assets/Scripts/PlayAgain.cs:30)
PlayAgain.Update () (at Assets/Scripts/PlayAgain.cs:17)

 

So, .. did you check what i wrote?