Problem with checking if null

Questions & Answers
1

I am making a small riddle game and you are given a random riddle. When you solve the riddle, the riddle game object is destroyed. I made an array with all the riddles and the script randomly picks 1 riddle. The problem is that if(currentRiddle == null) doesn’t work and it moves to if(currentRiddle != null) which works and it causes an error. Is there any way to fix this?

public void PickRandomRiddle()
{
    
    index = Random.Range(0, Riddles.Length);      
    currentRiddle = Riddles[index];
    

    if (currentRiddle == null)
    {
        PickRandomRiddle();
    }
    else if(currentRiddle != null)
    {
        currentRiddle.SetActive(true);
        print(currentRiddle.name);
    }
    
   
}
2

Because currentRiddle have a reference ‘Riddles[index]’ and it always will be not null.
And error?