Bug 431508

Split from https://bugs.kde.org/show_bug.cgi?id=426047 # 26


- What I was doing when the application crashed:
Configuring global shotcuts

- Unusual behavior I noticed:
I saved the shortcuts with apply button but they didn't actually works, also all shorcuts are unconfigured, I can't do an Alt + Tab

- Custom settings of the application:

-- Backtrace (Reduced):
#4  0x00007fcd25320504 in KGlobalShortcutInfo::componentUniqueName() const () from /lib64/libKF5GlobalAccel.so.5
#6  0x00007fccf0cad232 in QtPrivate::QFunctorSlotObject<GlobalAccelModel::addApplication(QString const&, QString const&)::{lambda()#2}::operator()() const::{lambda()#2}, 0, QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) () from /usr/lib64/qt5/plugins/kcms/kcm_keys.so
#7  0x00007fcd2670b386 in void doActivate<false>(QObject*, int, void**) () from /lib64/libQt5Core.so.5
#8  0x00007fcd254ae383 in QDBusPendingCallWatcher::finished(QDBusPendingCallWatcher*) () from /lib64/libQt5DBus.so.5
#9  0x00007fcd26703d1e in QObject::event(QEvent*) () from /lib64/libQt5Core.so.5



----- 

Reading the code it's clear what's wrong

        connect(infoWatcher, &QDBusPendingCallWatcher::finished, this, [=] {


A reply can be valid but empty. At which point calling info[0].componentUniqueName(); 
 obviously crashes.

I don't know if it's safe to just guard in the lambda.