Unplugging an external monitor makes gnome-shell crash
First reported by @daniel.playfair.cal in issue #81.
Excerpt from #81 (comment 97718):
With lfrb/mutter#wip/issue81#93ac74ad13f3973a21d097de6bd232e900571ffc (https://github.com/hedgepigdaniel/pkbuild-mutter/blob/wip/issue81/PKGBUILD)
Starting up and logging in with both external screens works
Unplugging my 1920x1080 external HDMI monitor causes a gnome-shell crash (Different trace from the previous crash I got in similar circumstances).