I'm not 100% sure why it happened, all that I know is that I had the my system suspended for quite some time and maybe the battery was drained. When I resumed, I saw a crash symbol in the system tray and shortly after that plasmashell also crashed.

Backtrace:

#0  0x00007f7c858f28d7 in __GI_raise (sig=11) at ../sysdeps/unix/sysv/linux/raise.c:55
#1  0x00007f7c876e8b14 in KCrash::defaultCrashHandler(int) () at /usr/lib64/libKF5Crash.so.5
#2  0x00007f7c858f2950 in <signal handler called> () at /lib64/libc-2.22.so
#3  0x00007f7c874b54d3 in QHash<PowerDevil::Action*, QHashDummyValue>::erase(QHash<PowerDevil::Action*, QHashDummyValue>::const_iterator) (this=this@entry=0x1fad390, it=it@entry=...)
    at /usr/include/qt5/QtCore/qhash.h:857
#4  0x00007f7c874ade5e in PowerDevil::Core::onResumingFromIdle() (i=..., this=0x1fad390)
    at /usr/include/qt5/QtCore/qset.h:197
#5  0x00007f7c874ade5e in PowerDevil::Core::onResumingFromIdle() (i=..., this=0x1fad390)
    at /usr/include/qt5/QtCore/qset.h:193
#6  0x00007f7c874ade5e in PowerDevil::Core::onResumingFromIdle() (this=this@entry=0x1fad310)
    at /usr/src/debug/powerdevil-5.9.4/daemon/powerdevilcore.cpp:798
#7  0x00007f7c874b0218 in PowerDevil::Core::loadProfile(bool) (this=this@entry=0x1fad310, force=force@entry=false) at /usr/src/debug/powerdevil-5.9.4/daemon/powerdevilcore.cpp:346
#8  0x00007f7c874b3cb8 in PowerDevil::Core::onAcAdapterStateChanged(PowerDevil::BackendInterface::AcAdapterState) (this=0x1fad310, state=PowerDevil::BackendInterface::Plugged)
    at /usr/src/debug/powerdevil-5.9.4/daemon/powerdevilcore.cpp:624
#9  0x00007f7c874cf15b in PowerDevil::Core::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>)
    at /usr/src/debug/powerdevil-5.9.4/build/daemon/powerdevilcore_automoc.dir/moc_powerdevilcore_SR3RJSZTCRXVIY.cpp:226
#10 0x00007f7c862780d5 in QMetaObject::activate(QObject*, int, int, void**) ()
    at /usr/lib64/libQt5Core.so.5.8.0
#11 0x00007f7c874ce06e in PowerDevil::BackendInterface::acAdapterStateChanged(PowerDevil::BackendInterface::AcAdapterState) (this=this@entry=0x1fdef30, _t1=_t1@entry=PowerDevil::BackendInterface::Plugged)
    at /usr/src/debug/powerdevil-5.9.4/build/daemon/powerdevilcore_automoc.dir/moc_powerdevilback_I25NWGJZD7ADF4.cpp:250
#12 0x00007f7c874ab0bb in PowerDevil::BackendInterface::setAcAdapterState(PowerDevil::BackendInterface::AcAdapterState) (this=this@entry=0x1fdef30, state=state@entry=PowerDevil::BackendInterface::Plugged)
    at /usr/src/debug/powerdevil-5.9.4/daemon/powerdevilbackendinterface.cpp:142
#13 0x00007f7c701d4251 in PowerDevilUPowerBackend::slotPropertyChanged() (this=0x1fdef30)
    at /usr/src/debug/powerdevil-5.9.4/daemon/backends/upower/powerdevilupowerbackend.cpp:640
#14 0x00007f7c701d4399 in PowerDevilUPowerBackend::onPropertiesChanged(QString const&, QMap<QString, QVariant> const&, QStringList const&) (this=<optimized out>, ifaceName=..., changedProps=..., invalidatedProps=...)
    at /usr/src/debug/powerdevil-5.9.4/daemon/backends/upower/powerdevilupowerbackend.cpp:652
#15 0x00007f7c701e3814 in PowerDevilUPowerBackend::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) (_o=_o@entry=0x1fdef30, _c=_c@entry=QMetaObject::InvokeMetaMethod, _id=_id@entry=12, _a=_a@entry=0x7ffc9b0f0810)
    at /usr/src/debug/powerdevil-5.9.4/build/daemon/backends/powerdevilupowerbackend_automoc.dir/moc_powerdevilupow_HYK6MXZV2XCI6O.cpp:144
#16 0x00007f7c701e3ee3 in PowerDevilUPowerBackend::qt_metacall(QMetaObject::Call, int, void**) (this=0x1fdef30, _c=QMetaObject::InvokeMetaMethod, _id=12, _a=0x7ffc9b0f0810)
    at /usr/src/debug/powerdevil-5.9.4/build/daemon/backends/powerdevilupowerbackend_automoc.dir/moc_powerdevilupow_HYK6MXZV2XCI6O.cpp:205
#17 0x00007f7c866c249b in  () at /usr/lib64/libQt5DBus.so.5
#18 0x00007f7c86279886 in QObject::event(QEvent*) () at /usr/lib64/libQt5Core.so.5.8.0
#19 0x00007f7c8625030c in QCoreApplication::notify(QObject*, QEvent*) () at /usr/lib64/libQt5Core.so.5.8.0
#20 0x00007f7c86250245 in QCoreApplication::notifyInternal2(QObject*, QEvent*) ()
    at /usr/lib64/libQt5Core.so.5.8.0
#21 0x00007f7c862522a3 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) ()
    at /usr/lib64/libQt5Core.so.5.8.0
#22 0x00007f7c8629f043 in postEventSourceDispatch(_GSource*, int (*)(void*), void*) ()
    at /usr/lib64/libQt5Core.so.5.8.0
#23 0x00007f7c7fcbc134 in g_main_context_dispatch () at /usr/lib64/libglib-2.0.so.0
#24 0x00007f7c7fcbc388 in  () at /usr/lib64/libglib-2.0.so.0
#25 0x00007f7c7fcbc42c in g_main_context_iteration () at /usr/lib64/libglib-2.0.so.0
#26 0x00007f7c8629e88c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
    at /usr/lib64/libQt5Core.so.5.8.0
#27 0x00007f7c8624e6ab in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) ()
    at /usr/lib64/libQt5Core.so.5.8.0
#28 0x00007f7c86256344 in QCoreApplication::exec() () at /usr/lib64/libQt5Core.so.5.8.0
#29 0x00000000004052bb in main(int, char**) (argc=1, argv=<optimized out>)
    at /usr/src/debug/powerdevil-5.9.4/daemon/powerdevilapp.cpp:151