iTween Question (New to coding)

So I am following this tutorial and I ran into the compile error of this:

 NullReferenceException: Object reference not set to an instance of an object
 iTween.CleanArgs (System.Collections.Hashtable args) (at Assets/Plugins/Pixelplacement/iTween/iTween.cs:6458)
 iTween.MoveTo (UnityEngine.GameObject target, System.Collections.Hashtable args) (at Assets/Plugins/Pixelplacement/iTween/iTween.cs:1276)
 ParticleFollow.Start () (at Assets/ParticleFollow.cs:11)
 

I know it is telling me there is something wrong with it trying to actually move it to the reference but I am not exactly sure what. My script for the particle movement is this:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class ParticleFollow : MonoBehaviour {
 
     public string pathName;
     public float time;
 
     void Start () {
         iTween.MoveTo ( gameObject, iTween.Hash("path", iTweenPath.GetPath (pathName), "easetype", iTween.EaseType.easeInOutSine, "time", time) );    
     }
     
 }
 

And the chunk of code it is wanting me to fix is this:

             if(item.Value.GetType() == typeof(System.Int32)){

Could anyone offer me some advice on how to fix this? Or at least point me in the right direction? I am really really new to unity and C# so it's a bit overwhelming when knowing what to look for.