Visual Studio Code – Why do I get an error why trying to use the ?. operator?

I’m developing a game where I can destroy objects, including those that may be playing animations. I used the null-conditional operator (?.) to avoid errors, but I’m still encountering issues. In my code, I have a PlayAnimation method that uses the ?. operator to call the Play method on the anim object. However, I’m getting errors even with this approach. I’m using the 2022 version of Visual Studio

using UnityEngine;

public class Door : MonoBehaviour
{
    public GameObject door;
    public Animator anim;

    public bool open = false;

    private void Update()
    {
        PlayAnimation(open ? "DoorOpen" : "DoorClose");
    }

    private void OnTriggerStay(Collider other)
    {
        open = other.CompareTag("Player");
    }

    private void OnTriggerExit(Collider other)
    {
        open = false;
    }

    private void PlayAnimation(string state)
    {
        anim?.Play(state);
    }
}