To help with debugging some other problem, I had selected "Keep launcher open" and "Open output log" options. Frequently (but not always) when the game exits, the launcher crashes with a segfault. The crash report from the OS is attached.

I'm turning off the output log option and I'll report back on that. Apparently, you have to be using the game for more than just a few minutes before the crash becomes probable, so some quick testing with and without the logging option didn't crash the launcher.