NullReferenceException: Object reference not set to an instance of an object

I keep getting this error from my script, its not effecting the gameplay at all as far as i know, however it is getting annoying seeing it in the console every time i test

 using UnityEngine;
 using System.Collections;
 
 public class SpawnPointScript : MonoBehaviour {
 
     private Seeker seeker;
 
     private Transform player;
 
     public bool enablePlayerChecking;
 
     [HideInInspector]
     public bool canSpawn;
     
     private float cooldown;
     private float rateOfRefresh;
 
     private Vector3 lastPathNode;
 
     // Use this for initialization
     void Start () {
         rateOfRefresh = 0.5f;
         cooldown = 0;
 
         seeker = GetComponent<Seeker>();
 
         player = GameObject.FindGameObjectWithTag("Player").GetComponent<Transform>();
 
         enablePlayerChecking = true;
     
     }
     
     // Update is called once per frame
     void Update () {
         Debug.Log("Start of update");
         if (cooldown > 0) {
             cooldown -= Time.deltaTime;
         }
 
 
         if (cooldown <= 0) {
             seeker.StartPath(transform.position, player.position);
 
             ***lastPathNode = seeker.lastCompletedVectorPath[seeker.lastCompletedVectorPath.Count - 1];***
 
             float dist = Vector3.Distance(lastPathNode, player.position);
 
             if (dist <= 3) {
                 Debug.Log("Path returns true");
                 canSpawn = true;
             }else {
                 Debug.Log("Path returns null");
                 canSpawn = false;
             }
 
             cooldown = rateOfRefresh;
 
 
         }
     
     }
 
 
 }

the error is specifically coming from line 44

thanks in advance

EDIT:

NullReferenceException: Object reference not set to an instance of an object SpawnPointScript.Update () (at Assets/Scripts/Evironment Scripts/SpawnPointScript.cs:44)

thats the error