refactor: sprite sizing

packages/pinball_components/lib/src/components/alien_bumper.dart

@@ -113,9 +113,8 @@ class _AlienBumperSpriteGroupComponent
       AlienBumperSpriteState.inactive:
           Sprite(gameRef.images.fromCache(_offAssetPath)),
     };
-
     this.sprites = sprites;
-    size = sprites[AlienBumperSpriteState.active]!.originalSize / 10;
+    size = sprites.entries.first.value.originalSize / 10;
 
     current = AlienBumperSpriteState.active;
   }

packages/pinball_components/lib/src/components/sparky_bumper.dart

@@ -129,7 +129,7 @@ class _SparkyBumperSpriteGroupComponent
           Sprite(gameRef.images.fromCache(_offAssetPath)),
     };
     this.sprites = sprites;
-    size = sprites[SparkyBumperSpriteState.active]!.originalSize / 10;
+    size = sprites.entries.first.value.originalSize / 10;
 
     current = SparkyBumperSpriteState.active;
   }