If my NSDocument.canConcurrentlyReadDocuments(ofType:) implementation returns true, often when launching the app, an untitled document is created regardless whether another document is restored. If document reading is not concurrent, an untitled document is only created when no other document is restored, as expected.
The issue happens on most app launches when a document is restored. If the restored document takes long to load (which can be simulated by putting sleep(1) in the Document.read(from:ofType:) implementation), the issue always happens.
Is this expected, or is there a workaround?
I created FB25340015.