Trying to cancel syncing while no sync job is running crashes sync-monitor
The sync status is not correctly reflected in lomiri-calendar-app (see ubports/development/apps/lomiri-calendar-app#222 (closed)) and trying to cancel a non-existing sync job crashes sync-monitor.
Backtrace:
#0 SyncAccount::cancel (this=0x0, sources=...) at ./src/sync-account.cpp:95
#1 0x000055555557f85a in SyncDaemon::cancel (this=0x55555560da80, syncAcc=<optimized out>, sources=...) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h:151
#2 0x000055555557fb8b in SyncDaemon::cancel (this=0x55555560da80, accountId=<optimized out>, sourceNames=...) at ./src/sync-daemon.cpp:241
#3 0x0000555555582c07 in SyncDBus::cancelAll (this=<optimized out>) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h:151
#4 0x0000555555593883 in SyncDBus::qt_static_metacall (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=0x7fffffffdd10) at ./obj-x86_64-linux-gnu/src/synq-lib_autogen/EWIEGA46WW/moc_sync-dbus.cpp:219
#5 0x00005555555948f3 in SyncDBus::qt_metacall (this=0x7fffcc01a790, _c=QMetaObject::InvokeMetaMethod, _id=11, _a=0x7fffffffdd10) at ./obj-x86_64-linux-gnu/src/synq-lib_autogen/EWIEGA46WW/moc_sync-dbus.cpp:358
#6 0x00007ffff791063b in ?? () from /lib/x86_64-linux-gnu/libQt5DBus.so.5
#7 0x00007ffff7915797 in ?? () from /lib/x86_64-linux-gnu/libQt5DBus.so.5
#8 0x00007ffff7915f7e in ?? () from /lib/x86_64-linux-gnu/libQt5DBus.so.5
#9 0x00007ffff7918ae2 in ?? () from /lib/x86_64-linux-gnu/libQt5DBus.so.5
#10 0x00007ffff7cfbc0a in QObject::event(QEvent*) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#11 0x00007ffff7ccf7d7 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#12 0x00007ffff7cd2478 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#13 0x00007ffff7d27e17 in ?? () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#14 0x00007ffff6fcd17d in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#15 0x00007ffff6fcd400 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#16 0x00007ffff6fcd4a3 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#17 0x00007ffff7d27415 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#18 0x00007ffff7cce39b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#19 0x00007ffff7cd6106 in QCoreApplication::exec() () from /lib/x86_64-linux-gnu/libQt5Core.so.5
#20 0x00005555555665fc in main (argc=<optimized out>, argv=0x7fffffffe488) at ./src/main.cpp:67