d092e913d6
There seems to be a kernel race when one disconnects an external monitor connected to a DisplayPort via a USB-C adapter. The race results in a connector being reported as connected, but without any modes supported. This had the side effect that we tried to set a preferred mode to the first listed mode, but as no modes were available, we instead tried to dereference the first element of a NULL array, causing a segmentation fault. Mitigate this by skipping adding output if no supported modes are advertised and the output doesn't support scaling, while moving the fallback path for calculating a preferred output mode to after possibly adding the common modes, to avoid the unvolentary NULL dereference. https://bugzilla.gnome.org/show_bug.cgi?id=789501