How attach and destroy Collider and Rigidbody in runtime?

Unity Engine
,
1

I build a fighting game, when I hit the punch button, a collider and rigidbody attached to the palm. After that, I want to destroy both collider and rigidbody. Otherwise, it will keep reduce energy bar even no hit punch button.

function AddColliders()
{
	var p_l_palm : GameObject = GameObject.Find("Player/man/Pelvis/Spine/Spine.2/Heart/L_Shoulder/L_Elbow/L_Hand/L_Palm");
	var p_r_palm : GameObject = GameObject.Find("Player/man/Pelvis/Spine/Spine.2/Heart/R_Shoulder/R_Elbow/R_Hand/R_Palm");
	
	var p_collider_l_palm : SphereCollider = p_l_palm.AddComponent(SphereCollider);
    var p_collider_r_palm : SphereCollider = p_r_palm.AddComponent(SphereCollider);
    
    p_collider_l_palm.radius = 0.1;
    p_collider_r_palm.radius = 0.1;
    
    var p_rigidbody_l_palm : Rigidbody = p_l_palm.AddComponent(Rigidbody);
    var p_rigidbody_r_palm : Rigidbody = p_r_palm.AddComponent(Rigidbody);
}

function Update () {
Punch();
}

function Punch()
{
	if(PunchJoystick.IsFingerDown()) 
	{	
		Character.animation.Play ("punch"); 
		AddColliders();
        }
}

But it throws:

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

in this line:
p_collider_l_palm.radius = 0.1;

If I add

    Destroy(p_rigidbody_l_palm);
    Destroy(p_rigidbody_r_palm);
        
    Destroy(p_collider_l_palm);
    Destroy(p_collider_r_palm);

There are no collider and rigidbody to be attached.

How should I fix it?

2

This suggests that the collider doesn’t get added properly, but I would expect there are other errors if this is the case. Do you see any other error messages in the console window?