Space Shooter error message

I keep getting this reference in Space Shooter

NullReferenceException: Object reference not set to an instance of an object
Done_DestroyByContact.OnTriggerEnter (UnityEngine.Collider other) (at Assets/Done/Done_Scripts/Done_DestroyByContact.cs:39)

I got stumped when my laser pushed the Asteroid and itself off the screen.

My Asteroids are’t getting destroyed. Need help. Triggers are set also

Well that error means that you are trying to interact with a Gameobject that has not been set either by code or in your inspector.

Check the line 39 in your Donne_DestroyByContact script, there you will see you are trying to do something with a variable of a game object, so what you need to do and havent done yet is set the variable to a game object. So after that select the object that has the script and in there you will see something is missing.

If thats not the case please share the code so we can see where the problem is.