Object Pooling Script for Autorunner?

I'm getting an error message in my script and I just don't know what to do. Can I get some help?

Error Message: Assets\Scripts\TileManager.cs(45,58): error CS7036: There is no argument given that corresponds to the required formal parameter 'value' of 'Dictionary>.Add(int, List)'

  using System.Collections;
  using UnityEngine;
  using System.Collections.Generic;
  
  public class TileManager : MonoBehaviour
  {
      public GameObject[] tilePrefabs;
  
      Dictionary<int, List<GameObject>> tilePool = new Dictionary<int, List<GameObject>>();
  
      private Transform playerTransform;
      private float spawnZ = -10f;
      private float tileLength = 27.7016f;
      private float safeZone = 22.5f;
      private int amnTilesOnScreen = 4;
      private int lastPrefabIndex = 0;
  
      private List<GameObject> activeTiles;
  
      // Start is called before the first frame update
      private void Start()
      {
          activeTiles = new List<GameObject>();
          playerTransform = GameObject.FindGameObjectWithTag("Player").transform;
  
          for (int i = 0; i < amnTilesOnScreen; i++)
          {
              if (i < 2)
                  SpawnTile(0);
              else
                  SpawnTile();
          }
      }
  
      // Update is called once per frame
      private void Update()
      {
          if (playerTransform.position.z - safeZone > (spawnZ - amnTilesOnScreen * tileLength))
          {
              SpawnTile();
              DeleteTile();
          }
      }
  
      private void SpawnTile(int prefabIndex = -1)
      {
          //make sure prefabIndex is set correctly. 
  
          if (!tilePool.ContainsKey(prefabIndex)) tilePool.Add(new List<GameObject>());
          GameObject go = tilePool[prefabIndex].Find(x => !x.activeSelf); // find disabled gameobject to reuse
          if (go == null)
          {
              go = Instantiate(tilePrefabs[prefabIndex]) as GameObject;
              tilePool[prefabIndex].Add(go);
          }
          //set position for go and else
      }
  
      private void DeleteTile()
      {
          activeTiles[0].SetActive(false);//disable for reuse
          activeTiles.RemoveAt(0);
      }
  
      private int RandomPrefabIndex()
      {
          if (tilePrefabs.Length <= 1)
              return 0;
  
          int randomIndex = lastPrefabIndex;
          while (randomIndex == lastPrefabIndex)
          {
              randomIndex = Random.Range(0, tilePrefabs.Length);
          }
  
          lastPrefabIndex = randomIndex;
          return randomIndex;
      }
  
  }