It looks like GNOME Shell passes some bad icon data into GTK+, which
results in a null filename that gets dereferenced.  (GNOME Shell is not
in the backtrace – it tells GTK+ to run this thread from the
“load_texture_async” function in “st-texture-cache.c”.

I think the “bad” user files are not the root cause here.  There’s
definitely something wrong with notifications.  (I just plugged in a USB
drive and, sure enough, GNOME Shell crashed.)  The notification daemon
code is written in JavaScript (“js/ui/notificationDaemon.js”).  I
glanced at it and its Git history, but couldn’t find anything.


-- Tim