Question Change sprite while scheme input manager changed

Hi from this code I want change sprite when I use different input, in this case between keyboard and xbox controller.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.InputSystem;
5.  
6. public class InputSchemeSprite : MonoBehaviour
7. {
8.     PlayerInput input;
9.     SpriteRenderer spriteRenderer;
10.  
11.     [SerializeField] private Sprite keyboardSprite;
12.     [SerializeField] private Sprite controllerSprite;
13.  
14.     private void Start()
15.     {
16.         input = GetComponent<PlayerInput>();
17.         spriteRenderer = GetComponent<SpriteRenderer>();
18.         CurrentScheme();
19.     }
20.  
21.     private void Update()
22.     {
23.         CurrentScheme();
24.     }
25.     void CurrentScheme()
26.     {
27.         if(input.currentControlScheme == "Keyboard")
28.         {
29.             spriteRenderer.sprite = keyboardSprite;
30.             Debug.Log("Keyboard");
31.         }
32.         else if (input.currentControlScheme == "Gamepad")
33.         {
34.             spriteRenderer.sprite = controllerSprite;
35.             Debug.Log("Controller");
36.         }
37.     }
38. }

But this code doesnt work, unity give me this error code

NullReferenceException: Object reference not set to an instance of an object
InputSchemeSprite.CurrentScheme () (at Assets/Scripts/InputSchemeSprite.cs:27)
InputSchemeSprite.Update () (at Assets/Scripts/InputSchemeSprite.cs:23)

Please if someone can help me to resolve this, thanks