Tiny fix for sprite editor

dist/preview release/packagesSizeBaseLine.json

@@ -1 +1 @@
-{"thinEngineOnly":115859,"engineOnly":152262,"sceneOnly":511410,"minGridMaterial":644687,"minStandardMaterial":788187}
+{"thinEngineOnly":115886,"engineOnly":152289,"sceneOnly":511469,"minGridMaterial":644774,"minStandardMaterial":788500}

src/Sprites/spriteManager.ts

@@ -838,7 +838,7 @@ export class SpriteManager implements ISpriteManager {
                     if (request.status == 200) {
                         var snippet = JSON.parse(JSON.parse(request.responseText).jsonPayload);
                         let serializationObject = JSON.parse(snippet.spriteManager);
-                        let output = SpriteManager.Parse(serializationObject, scene, rootUrl);
+                        let output = SpriteManager.Parse(serializationObject, scene || Engine.LastCreatedScene, rootUrl);
 
                         output.snippetId = snippetId;