You can quit while saving

And if you do, the save gets cut off, since `System.exit(0)` is called.

What a nasty problem. But that's what happens when you forcibly shut down the JVM. We could work around it by adding a shutdown hook which blocks until saving is complete, but that could create its own problems (deadlock, etc.)...

Start by locating the System.exit(0) call and tracing how saving completes before shutdown. Determine a safe, agreed shutdown behavior that does not cut off saves, while checking for the deadlock concerns raised in the issue; done means quitting cannot interrupt an active save.

Written by the indexing model from the issue text.