ARCore: Nullpointer exception after touchphase ended. Drag and Drop problem.

I made a script in ARCore to drag and drop three objects: A shield, a cube and a dice. Each gameobject has a Outline shader script to mark the object with outline color after touching it. The script is almost working, but at the beginning when the app started I always receive an error nullpointer exception after lifting my finger from the screen. After I tapped on one of the three gameobjects the exception is gone. In my code I added a condition to check if the gameobject is set with a certain component or not. I want to disable the rigidbody of the dice, because it is complicated to drag an object which has a rigidbody.

 using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Timers;
 using UnityEngine;
 using UnityEngine.UI;
 using UnityEngine.XR.ARFoundation;
 
 public class Test : MonoBehaviour
 {
     private int tapCount = 0;
     private GameObject placement;
     public Camera arCamera;
     private float doubleTapTimer = 0;
     private Color oldColor;
 
     private float range;
     private bool movingVertical = false;
     private bool moving = false;
 
     private void Start()
     {
         range = 1000f;
         oldColor = new Color(0.96f, 0.46f, 0.078f);
     }
 
     void Update()
     {
         doubleTapTimer += Time.deltaTime;
         
         for (int i = 0; i < Input.touchCount; i++)
         {
             Ray ray = arCamera.ScreenPointToRay(Input.GetTouch(i).position);
             RaycastHit hitObject;
             
             // One-Finger Touch one time
             if (i == 0)
             {
                 if (Input.GetTouch(i).phase == TouchPhase.Began)
                 {
                     tapCount += 1;
                 }
 
                 if (tapCount == 0 && !moving)
                 {
                     if (Physics.Raycast(ray, out hitObject, range))
                     {
                         if (hitObject.transform.name != null)
                             Debug.Log(hitObject.transform.name);
                         
                         switch (hitObject.transform.name)
                         {
                             case "Cube":
                             case "WhiteDice":
                             case "Shield":
                                 ActivateObject(hitObject);
                                 moving = true;
 
                                 break;
                             default:
                                 ResetObject(placement);
                                 break;
                         }
                     }
                 }
 
                 // One-Finger Touch two times
 
                 if (tapCount == 1 && doubleTapTimer < 0.5f && !(moving))
                 {
 
                     if (Physics.Raycast(ray, out hitObject, range))
                     {
 
                         switch (hitObject.transform.name)
                         {
                             case "Cube":
                             case "WhiteDice":
                             case "Shield":
                                 movingVertical = true;
                                 placement.GetComponent<Outline>().OutlineColor = Color.blue;
                                 break;
                             default:
                                 break;
                         }
                     }
 
                 }
 
 
                 if (moving)
                 {
                     if (Physics.Raycast(ray, out hitObject, range))
                     {
                         if (placement.name.Contains("WhiteDice") && 
                             placement.GetComponent<DiceScript>() != null &&
                             placement.GetComponent<Rigidbody>() != null)
                         {
                             placement.GetComponent<DiceScript>().enabled = false;
                             placement.GetComponent<Rigidbody>().isKinematic = true;
                         }
                         
                         if (!movingVertical)
                         {
                             placement.transform.position = new Vector3(hitObject.point.x,
                                 placement.transform.position.y, hitObject.point.z);
                         }
                         else if (movingVertical)
                         {
                             placement.GetComponent<Outline>().OutlineColor = Color.blue;
                             placement.transform.position = new Vector3(placement.transform.position.x,
                                 hitObject.point.y, placement.transform.position.z);
                         }
 
                     }
                 }
 
                 if (doubleTapTimer > 0.5f)
                 {
                     doubleTapTimer = 0f;
                     tapCount = 0;
                 }
             }
 
             // Double Finger Touch one times
             if (Input.GetTouch(i).phase == TouchPhase.Ended)
             {
                 moving = false;
                 movingVertical = false;
                 if (placement != null)
                 {
                     placement.GetComponent<Outline>().enabled = false;
                 }
 
                 if (movingVertical)
                 {
                     tapCount = 0;
                     doubleTapTimer = 0.0f;
                 }
                 
                 if (placement.name.Contains("WhiteDice") && 
                     placement.GetComponent<DiceScript>() != null &&
                     placement.GetComponent<Rigidbody>() != null)
                 {
                     placement.GetComponent<DiceScript>().enabled = true;
                     placement.GetComponent<Rigidbody>().isKinematic = false;
                 }
             }
         }
     }
 
     public void ActivateObject(RaycastHit hitObject)
     {
         ResetObject(placement);
         doubleTapTimer = 0f;
         placement = hitObject.transform.gameObject;
         placement.GetComponent<Outline>().enabled = true;
         placement.GetComponent<Outline>().OutlineColor = oldColor;
     }
     
     public void ResetObject(GameObject placement)
     {
         if (placement != null)
         {
             placement.GetComponent<Outline>().OutlineColor = oldColor;
             placement.GetComponent<Outline>().enabled = false;
             placement = null;
             moving = false;
             tapCount = 0;
             doubleTapTimer = 0f;
         }
     }
 }