Unintentionally created a similar post here https://forums.developer.apple.com/forums/thread/756124

Thank you! That’s what i needed to know.

Thank you! That's exactly what I need.

Thank you!

I managed to get rid of the crash by taking out the continuation into a nonisolated function, but I don't know why it helped and what the root cause of the issue is.

Thank you for your response. I was under the impression that it was required to have a scene inside the App body. Your comment made me check, and it turns out the body can be empty. So it is my fault for not checking first. And you are right, SMAppService works for my case.