Displaying Prefab Sprite as Texture on GUI Elements

I am trying to get a list of "weapons" from a folder of prefabs in my project and then display them in a GUI Box to signify a trading system where the sprite is previewed on purchase.

I have managed to read all of the prefabs and my debugs show that they are correctly read and the correct names are listed.

I managed to read them in as such:

     DirectoryInfo dir = new DirectoryInfo("Assets/Prefabs/Pickups/Melee");
     foreach (FileInfo f in dir.GetFiles("*.prefab"))
     {
         Debug.Log("Assets/Prefabs/Pickups/Melee/"+f.FullName);
         weapons.Add(Resources.Load("Assets/Prefabs/Pickups/Melee/"+f.FullName) as GameObject);
     }

T$$anonymous$$s includes the debug that correctly displays the name of each item as it's added into the ArrayList.

I then attempt to pull a Texture from these objects to show them on the GUI as such:

         foreach(GameObject wep in weapons)
         {
             // Convert Sprite to Texture
             var sprite = wep.GetComponent<SpriteRenderer>().sprite;
             var croppedTexture = new Texture2D( (int)sprite.rect.width, (int)sprite.rect.height );
             
             var pixels = sprite.texture.GetPixels( (int)sprite.textureRect.x,
                                                   (int)sprite.textureRect.y,
                                                   (int)sprite.textureRect.width,
                                                   (int)sprite.textureRect.height );
             
             croppedTexture.SetPixels( pixels );
             croppedTexture.Apply();
             
             // Draw Box with Weapon Texture
             GUI.Box(new Rect(windowRect.x+20, windowRect.y+(weaponCount*50), 40, 40), croppedTexture);
             weaponCount++;
         }

I got t$$anonymous$$s snippet from here.

The issue I get is a null reference when I attempt to pull the SpriteRenderer.sprite variable from the object. I'm not sure how t$$anonymous$$s could be going wrong and would appreciate if anyone might know what the issue may be.

Each prefab looks somet$$anonymous$$ng like t$$anonymous$$s: http://i.imgur.com/vkNrXML.png (none of the variables of the script are yet referenced)

The sprites themselves look somet$$anonymous$$ng like t$$anonymous$$s: http://i.imgur.com/p6jsn2r.png (they are single sprites because their animation is handled via code)

I seem to be doing somet$$anonymous$$ng wrong but I'm not quite sure exactly what. Any assistance would be fantastic, thanks.