NPC won't move after adding chase code.

Hey there! I'm following a Pluralsight tutorial on Unity Fundamentals. I'm currently working on the NPC. The NPC moves fine from waypoint to waypoint until I add the code to chase the player, it won't move at all. Below is my NPCController script.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.AI;
 
 public class NPCController : MonoBehaviour
 {
     public float patrolTime = 10f;
     public float aggroRange = 10f;
     public Transform[] waypoints;
 
     private int index;
     private float speed, agentSpeed;
     private Transform player;
 
     //private Animator anim;
     private NavMeshAgent agent;
 
     private void Awake()
     {
         //anim = GetComponent<Animator>();
         agent = GetComponent<NavMeshAgent>();
         if (agent != null) { agentSpeed = agent.speed; }
         player = GameObject.FindGameObjectWithTag("Player").transform;
         index = Random.Range(0, waypoints.Length);
 
         InvokeRepeating("Tick", 0, 0.5f);
 
         if (waypoints.Length > 0)
         {
             InvokeRepeating("Patrol", 0, patrolTime);
         }
     }
 
     void Patrol()
     {
         index = index == waypoints.Length - 1 ? 0 : index + 1;
     }
 
     void Tick()
     {
         agent.destination = waypoints[index].position;
         agent.speed = agentSpeed / 2;
 
         if (player != null && Vector3.Distance(transform.position, player.position) < aggroRange)
         {
             agent.destination = player.position;
             agent.speed = agentSpeed;
         }
     }
 }