Unity XR interaction Null Reference error

Question

Iam trying to get Vr Hand models using xr integration toolkit. iam using a hand controller script where it get input from controllers using and using another script which is on hand models to animate them, but iam getting a null reference exception error.

This is connected to the controller.

[RequireComponent(typeof(ActionBasedController))]
public class HandController : MonoBehaviour
{
    // Start is called before the first frame update
    ActionBasedController controller;
    public Hand hand;
    void Start()
    {
        controller = GetComponent<ActionBasedController>();
    }

    // Update is called once per frame
    void Update()
    {
        hand.SetGrip(controller.selectAction.action.ReadValue<float>());
        hand.SetTrigger(controller.selectAction.action.ReadValue<float>());
        
    }
}

this is the hand script to animate

public class Hand : MonoBehaviour
{

    Animator animator;
    private float gripTarget;
    private float triggerTarget;
    private float gripCurrent;
    private float triggerCurrent;
    public float speed;
    

    // Start is called before the first frame update
    void Start()
    {
        animator = GetComponent<Animator>();

    }

    // Update is called once per frame
    void Update()
    {
        UpdateHandAnimation();
    }

    internal void SetGrip(float v)
    {
        gripTarget = v;
    }

    internal void SetTrigger(float v)
    {
        triggerTarget = v;
    }

    void UpdateHandAnimation()
    {
        if (gripCurrent != gripTarget)
        {
            gripCurrent = Mathf.MoveTowards(gripCurrent, gripTarget, Time.deltaTime * speed);
            animator.SetFloat("Grip", gripCurrent);
        }
        else 
        {
             animator.SetFloat("Grip", 0);
        }

        if (triggerCurrent != triggerTarget)
        {
            triggerCurrent = Mathf.MoveTowards(triggerCurrent, triggerTarget, Time.deltaTime * speed);
            animator.SetFloat("Trigger", triggerCurrent);
        }
        else 
        {
             animator.SetFloat("Trigger", 0);
        }

    }
}