Nullable fixes, use Texture2d resource for rendering directly.

DaggerFramework/Source/SceneGraph/Entities/Sprite2d.cs

@@ -6,20 +6,18 @@ namespace DaggerFramework.SceneGraph
 {
     public class Sprite2d : Drawable2d
     {
-        public Texture2d Texture { get => _texture; set => _texture = value; }
+        public Texture2d Texture { get => _texture ?? Texture2d.Empty; set => _texture = value; }
 
         protected override void OnStart()
         {
             var renderer = Layer.Scene.Renderer;
-            _texId = renderer.LoadTexture(_texture);
         }
 
         public override void OnDraw(Renderer renderer)
         {
-            renderer.DrawTexture(_texId, Color.White);
+            renderer.DrawTexture(_texture!, Color.White);
         }
 
-        private Texture2d _texture;
-        private int _texId;
+        private Texture2d? _texture;
     }
 }