Comment 6 for bug 1666472

I'm pretty sure this occurs when closing an application. What happens is that ubuntu-app-launch is not very nice when closing X apps and will just kill Xmir out from underneath the applications. pasted sees that the X server is gone and produces this crash.

I have been working on moving all of the Xmir handling into Libertine and out of ubuntu-app-launch. When that is complete, Libertine will be responsible for killing Xmir, at which point, we can shut it down after all applications needing the display have closed.