How to fix NullReferenceException error?

Question

Unity

There is a bullet object on it there is a script with the OnTriggerEnter2D function. The problem is that when creating a bullet next to a wall, it will be destroyed after a collision, but when the bullet hits the wall, we get this error

NullReferenceException: Object reference not set to an instance of an object Bullet.OnTriggerEnter2D (UnityEngine.Collider2D col) (at Assets/Scripts/Bullet.cs:23)

PS On the 23rd line of the code, the curly brace OnTriggerEnter2D opens

Answer 1

The problem was in this line of codeif(!PV.IsMine) return;