IsValid

Destroying a GameObject or Component doesn't erase the C# reference. Any variable that was pointing to it still holds a non-null object - it's just a dead one. Accessing its properties will do nothing useful or throw an exception.

This is why you can't rely on a plain != null check:

// ❌ Wrong - the reference is still non-null after Destroy()
if ( myObject != null )
{
    myObject.DoSomething(); // might throw an exception or do nothing
}

// ✅ Correct
if ( myObject.IsValid() )
{
    myObject.DoSomething();
}

You do not need to check for null separately. myObject.IsValid() is safe even if myObject is null.

Common Patterns

Checking before use

void Update()
{
    if ( !_target.IsValid() ) return;

    var dist = WorldPosition.Distance( _target.WorldPosition );
}

Filtering a list after a frame

// Remove any destroyed targets from your list
_targets.RemoveAll( t => !t.IsValid() );

Callbacks and delayed code

Async gaps and timers are common places where objects can be destroyed between frames:

async Task ShootAfterDelay()
{
    await Task.DelaySeconds( 1.0f );

    // The object might have been destroyed during the delay
    if ( !this.IsValid() ) return;

    FireProjectile();
}