Please Help!!! I am new to Unity I want to create a GameObject through Scripting and add sprite to it......I have done that but there is an error "Object reference not set to an instance of an object" PLS HELP!!! ASAP!!!

I am having error on line : sr.sprite = Sprite.Create (tex, new Rect (0, 0, tex.width, tex.height), new Vector2 (6.2f, 1f))

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

Here is my code -:

 void Start () {
     
     
     UnityEngine.Object[] allSprites = AssetDatabase.LoadAllAssetsAtPath ("Assets/Sprites/full brick.png") ;
     
     ground = new GameObject ();
     ball = new GameObject ();
     ground.name = "Ground";
     ground.AddComponent<BoxCollider2D> ();
     ground.GetComponent<BoxCollider2D> ().isTrigger = false;
     SpriteRenderer sr = ground.AddComponent<SpriteRenderer> () as SpriteRenderer;
     Texture2D tex = allSprites[1] as Texture2D;
     sr.sprite = Sprite.Create (tex, new Rect (0, 0, tex.width, tex.height), new Vector2 (6.2f, 1f));
     ground.transform.position = new Vector3 (0.02f,-4.43f,1f);
     ground.transform.localScale = new Vector3 (6.2f, 1f, 1f);

 }