How do I make the camera follow a selected game object?

I need help setting up my camera to constantly follow a game object when it's selected. I already have a game object that detects whenever it is clicked, and a camera script that follows a specified game object. I just need to somehow make the camera follow the exact object when selected.

Selectable game object script

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Noggin : MonoBehaviour
 {
     private Animator anim;
     public GameObject gui;
 
     // Start is called before the first frame update
     void Start()
     {
         anim = GetComponent<Animator>();
     }
 
     void OnMouseDown()
     {
         gui.SetActive(true);
         if (this.gameObject != null)
         {
             DragCamera.instance.target = this.gameObject;
         }
     }
 }
 

Camera script

 using UnityEngine;
 using System;
 using System.Collections.Generic;
 using UnityEngine.EventSystems;
 
 
 public class DragCamera : MonoBehaviour
 {
     public static DragCamera instance;
 
     
     public event Action<Vector2> onStartTouch;
     
     public event Action<Vector2> onEndTouch;
     
     public event Action<Vector2> onTap;
     
     public event Action<Vector2> onSwipe;
     
     public event Action<float, float> onPinch;
 
     [Header("Tap")]
     [Tooltip("The maximum movement for a touch motion to be treated as a tap")]
     public float maxDistanceForTap = 40;
     [Tooltip("The maximum duration for a touch motion to be treated as a tap")]
     public float maxDurationForTap = 0.4f;
 
     [Header("Desktop debug")]
     [Tooltip("Use the mouse on desktop?")]
     public bool useMouse = true;
     [Tooltip("The simulated pinch speed using the scroll wheel")]
     public float mouseScrollSpeed = 2;
 
     [Header("Camera control")]
     [Tooltip("Does the script control camera movement?")]
     public bool controlCamera = true;
     [Tooltip("The controlled camera, ignored of controlCamera=false")]
     public Camera cam;
 
     [Header("UI")]
     [Tooltip("Are touch motions listened to if they are over UI elements?")]
     public bool ignoreUI = false;
 
     [Header("Bounds")]
     [Tooltip("Is the camera bound to an area?")]
     public bool useBounds;
 
     public float boundMinX = -150;
     public float boundMaxX = 150;
     public float boundMinY = -150;
     public float boundMaxY = 150;
 
     Vector2 touch0StartPosition;
     Vector2 touch0LastPosition;
     float touch0StartTime;
 
     bool cameraControlEnabled = true;
 
     bool canUseMouse;
 
     public float yPos = 2;
 
     public bool ZoomActive;
     public float interpVelocity;
     public float minDistance;
     public float followDistance;
     public Vector3 offset;
     Vector3 targetPos;
 
     public GameObject target;
 
     
     public bool isTouching { get; private set; }
 
     
     public Vector2 touchPosition { get { return touch0LastPosition; } }
 
     void Start()
     {
         canUseMouse = Application.platform != RuntimePlatform.Android && Application.platform != RuntimePlatform.IPhonePlayer && Input.mousePresent;
 
         targetPos = transform.position;
     }
 
     void Update()
     {
         if (useMouse && canUseMouse)
         {
             UpdateWithMouse();
         }
         else
         {
             UpdateWithTouch();
         }
 
         if (target)
         {
             Vector3 posNoZ = transform.position;
             posNoZ.z = target.transform.position.z;
 
             Vector3 targetDirection = (target.transform.position - posNoZ);
 
             interpVelocity = targetDirection.magnitude * 10f;
 
             targetPos = transform.position + (targetDirection.normalized * interpVelocity * Time.deltaTime);
 
             transform.position = Vector3.Lerp(transform.position, targetPos + offset, 0.25f);
 
         }
     }
 
     void LateUpdate()
     {
         CameraInBounds();
     }
 
     void UpdateWithMouse()
     {
         if (Input.GetMouseButtonDown(0))
         {
             if (ignoreUI || !IsPointerOverUIObject())
             {
                 touch0StartPosition = Input.mousePosition;
                 touch0StartTime = Time.time;
                 touch0LastPosition = touch0StartPosition;
 
                 isTouching = true;
 
                 if (onStartTouch != null) onStartTouch(Input.mousePosition);
             }
         }
 
         if (Input.GetMouseButton(0) && isTouching)
         {
             Vector2 move = (Vector2)Input.mousePosition - touch0LastPosition;
             touch0LastPosition = Input.mousePosition;
 
             if (move != Vector2.zero)
             {
                 OnSwipe(move);
             }
         }
 
         if (Input.GetMouseButtonUp(0) && isTouching)
         {
 
             if (Time.time - touch0StartTime <= maxDurationForTap
                && Vector2.Distance(Input.mousePosition, touch0StartPosition) <= maxDistanceForTap)
             {
                 OnClick(Input.mousePosition);
             }
 
             if (onEndTouch != null) onEndTouch(Input.mousePosition);
             isTouching = false;
             cameraControlEnabled = true;
         }
 
         if (Input.mouseScrollDelta.y != 0)
         {
             OnPinch(Input.mousePosition, 1, Input.mouseScrollDelta.y < 0 ? (1 / mouseScrollSpeed) : mouseScrollSpeed, Vector2.right);
         }
     }
 
     void UpdateWithTouch()
     {
         int touchCount = Input.touches.Length;
 
         if (touchCount == 1)
         {
             Touch touch = Input.touches[0];
 
             switch (touch.phase)
             {
                 case TouchPhase.Began:
                     {
                         if (ignoreUI || !IsPointerOverUIObject())
                         {
                             touch0StartPosition = touch.position;
                             touch0StartTime = Time.time;
                             touch0LastPosition = touch0StartPosition;
 
                             isTouching = true;
 
                             if (onStartTouch != null) onStartTouch(touch0StartPosition);
                         }
 
                         break;
                     }
                 case TouchPhase.Moved:
                     {
                         touch0LastPosition = touch.position;
 
                         if (touch.deltaPosition != Vector2.zero && isTouching)
                         {
                             OnSwipe(touch.deltaPosition);
                         }
                         break;
                     }
                 case TouchPhase.Ended:
                     {
                         if (Time.time - touch0StartTime <= maxDurationForTap
                             && Vector2.Distance(touch.position, touch0StartPosition) <= maxDistanceForTap
                             && isTouching)
                         {
                             OnClick(touch.position);
                         }
 
                         if (onEndTouch != null) onEndTouch(touch.position);
                         isTouching = false;
                         cameraControlEnabled = true;
                         break;
                     }
                 case TouchPhase.Stationary:
                 case TouchPhase.Canceled:
                     break;
             }
         }
         else if (touchCount == 2)
         {
             Touch touch0 = Input.touches[0];
             Touch touch1 = Input.touches[1];
 
             if (touch0.phase == TouchPhase.Ended || touch1.phase == TouchPhase.Ended) return;
 
             isTouching = true;
 
             float previousDistance = Vector2.Distance(touch0.position - touch0.deltaPosition, touch1.position - touch1.deltaPosition);
 
             float currentDistance = Vector2.Distance(touch0.position, touch1.position);
 
             if (previousDistance != currentDistance)
             {
                 OnPinch((touch0.position + touch1.position) / 2, previousDistance, currentDistance, (touch1.position - touch0.position).normalized);
             }
         }
         else
         {
             if (isTouching)
             {
                 if (onEndTouch != null) onEndTouch(touch0LastPosition);
                 isTouching = false;
             }
 
             cameraControlEnabled = true;
         }
     }
 
     void OnClick(Vector2 position)
     {
         if (onTap != null && (ignoreUI || !IsPointerOverUIObject()))
         {
             onTap(position);
         }
     }
     void OnSwipe(Vector2 deltaPosition)
     {
         if (onSwipe != null)
         {
             onSwipe(deltaPosition);
         }
 
         if (controlCamera && cameraControlEnabled)
         {
             if (cam == null) cam = Camera.main;
 
             cam.transform.position -= (cam.ScreenToWorldPoint(deltaPosition) - cam.ScreenToWorldPoint(Vector2.zero));
         }
     }
     void OnPinch(Vector2 center, float oldDistance, float newDistance, Vector2 touchDelta)
     {
         if (onPinch != null)
         {
             onPinch(oldDistance, newDistance);
         }
 
         if (controlCamera && cameraControlEnabled)
         {
             if (cam == null) cam = Camera.main;
 
             if (cam.orthographic)
             {
                 var currentPinchPosition = cam.ScreenToWorldPoint(center);
 
                 cam.orthographicSize = Mathf.Max(0.1f, cam.orthographicSize * oldDistance / newDistance);
 
                 var newPinchPosition = cam.ScreenToWorldPoint(center);
 
                 cam.transform.position -= newPinchPosition - currentPinchPosition;
             }
             else
             {
                 cam.fieldOfView = Mathf.Clamp(cam.fieldOfView * oldDistance / newDistance, 0.1f, 179.9f);
             }
         }
     }
 
     
     public bool IsPointerOverUIObject()
     {
 
         if (EventSystem.current == null) return false;
         PointerEventData eventDataCurrentPosition = new PointerEventData(EventSystem.current);
         eventDataCurrentPosition.position = new Vector2(Input.mousePosition.x, Input.mousePosition.y);
         List<RaycastResult> results = new List<RaycastResult>();
         EventSystem.current.RaycastAll(eventDataCurrentPosition, results);
         return results.Count > 0;
     }
 
     
     public void CancelCamera()
     {
         cameraControlEnabled = false;
     }
 
     void CameraInBounds()
     {
         if (controlCamera && useBounds && cam != null && cam.orthographic)
         {
             cam.orthographicSize = Mathf.Min(cam.orthographicSize, ((boundMaxY - boundMinY) / 2) - 0.001f);
             cam.orthographicSize = Mathf.Min(cam.orthographicSize, (Screen.height * (boundMaxX - boundMinX) / (2 * Screen.width)) - 0.001f);
 
             Vector2 margin = cam.ScreenToWorldPoint((Vector2.up * Screen.height / 2) + (Vector2.right * Screen.width / 2)) - cam.ScreenToWorldPoint(Vector2.zero);
 
             float marginX = margin.x;
             float marginY = margin.y;
 
             float camMaxX = boundMaxX - marginX;
             float camMaxY = boundMaxY - marginY;
             float camMinX = boundMinX + marginX;
             float camMinY = boundMinY + marginY;
 
             float camX = Mathf.Clamp(cam.transform.position.x, camMinX, camMaxX);
             float camY = Mathf.Clamp(cam.transform.position.y, camMinY, camMaxY);
 
             cam.transform.position = new Vector3(camX, camY, cam.transform.position.z);
         }
     }
 }

I tried the code I have right now but the game object script has an error and says "Object reference not set to an instance of an object"