GNOME Will No Longer Crash If Attaching A Monitor While The System Is Suspended
Bug #786929 that dates back nearly one year is now resolved. The issue comes down to "Attaching a monitor to laptop while in suspend and then waking up laptop will reliably crash gnome-shell."
This crash has been resolved in the Mutter back-end code by better tracking of each logical monitor to all monitors assigned to it. All monitors have a reference to each output and each output has a reference to any CRTC. With that better reference tracking, it should avoid a race condition on events between the display hot-plug event and trying to access the associated state.
That code is now merged into Mutter for what will be part of GNOME 3.30 in September.