Dear Maintainers, I think that this bug is an upstream bug. Plasma desktop should not give segmentation faults when upower is missing. Maxi already fixed the kscreen bug setting upower as recommendation, because the functionatily that upower gives to kscreen is remembering the last screens configurations after a reboot. That function fits into the recommendations, not dependency, so it is fixed now. But given a system that has the plasma desktop + kscreen, it should not give segmentation faults when the upower functionality is missing. Given that, I think that this is a upstream bug and that the ones that could fix this are the KDE developers.
Regards, Éter.