Wrong parent in some async flows

[dividedmind]

In some async scenarios, the event parent is not set correctly. Consider for example https://github.com/lukaszbulak/NestJS-TypeORM-Example and this AppMap resulting from npx appmap-node npm start dev & sleep 10 ; curl http://localhost:3000/boards:

As you can see, the SQL request is not under getBoards (as it should be) but is a separate root. Note this seems intermittent; here's another AppMap of an identical request, with no changes (not even a server restart):