I am adding to the Car Tutorial a particle system that is using the following script. If you take note the script is actually modified from the Pickup script from the 3D Platform Game. I want it so that when the car collides with the particle system, the top speed is increased. This script is added to the particle system. When I run the program, I am getting an error:

NullReferenceException: Object reference not set to an instance of an object UpdateTopSpeed.OnTriggerEnter (UnityEngine.Collider col) (at Assets/Scripts/JavaScripts/UpdateTopSpeed.js:41)

Does anyone know how to fix this error or how to change the code around so that I don't have to worry about the error. Note I have not changed much from the tutorial besides adding the particle system and creating this script called UpdateSpeed.

Thank you!

enum PickupType { Health = 0, FuelCell = 1 , TimeCell = 2}
var pickupType = PickupType.TimeCell;
var amount = 1;
var sound : AudioClip;
var soundVolume : float = 2.0;
var carStatus : Car;


private var used = false;
private var mover : DroppableMover;

function Start ()
{
    // do we exist in the level or are we instantiated by an enemy dying?
    mover = GetComponent(DroppableMover);
}

function ApplyPickup (carStatus : Car)
{
    // A switch...case statement may seem overkill for this, but it makes adding new pickup types trivial.
    switch (pickupType)
    {
       case PickupType.Health:
         carStatus.AddHealth(amount);
         break;

       case PickupType.FuelCell:
         carStatus.FoundItem(amount);
         break;

       case PickupType.TimeCell:
         carStatus.FoundItem(amount);
    }

    return true;
}

function OnTriggerEnter (col : Collider) {
    if(mover && mover.enabled) return;
    var carStatus : Car = col.GetComponent(Car);
    carStatus.GetComponent(Car).UpdateSpeed();

    //* Make sure we are running into a player
    //* prevent picking up the trigger twice, because destruction
    //  might be delayed until the animation has finished
    if (used || carStatus == null)
       return;

    if (!ApplyPickup (carStatus))
       return;

    used = true;

    // Play sound
    if (sound)
       AudioSource.PlayClipAtPoint(sound, transform.position, soundVolume);



    // If there is an animation attached.
    // Play it.
    if (animation && animation.clip)
    {
       animation.Play();
       Destroy(gameObject, animation.clip.length);
    }
    else
    {
       Destroy(gameObject);
    }
}

// Auto setup the pickup
function Reset ()
{
    if (collider == null)  
       gameObject.AddComponent(BoxCollider);
    collider.isTrigger = true;
}