Clock App crashes frequently when UCAlarmModel::clear() is called

There is a branch for the new clock app which adds support to update existing alarms. I have noticed during my testing that it sometimes crashes when saving/deleting a saved alarm.

I have pasted the gdb backtrace when the app crashes.

(gdb) bt
#0 0x00007fffcd1f9ec2 in UCAlarmModel::clear() ()
   from /usr/lib/x86_64-linux-gnu/qt5/qml/Ubuntu/Components/libUbuntuComponents.so
#1 0x00007fffcd1fa04d in UCAlarmModel::refresh() ()
   from /usr/lib/x86_64-linux-gnu/qt5/qml/Ubuntu/Components/libUbuntuComponents.so
#2 0x00007ffff5ec95b6 in QObject::event(QEvent*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#3 0x00007ffff6b3a6dc in QApplicationPrivate::notify_helper(QObject*, QEvent*)
    () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#4 0x00007ffff6b3f456 in QApplication::notify(QObject*, QEvent*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#5 0x00007ffff5e999d5 in QCoreApplication::notifyInternal(QObject*, QEvent*)
    () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#6 0x00007ffff5e9b827 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7 0x00007ffff5ef1243 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#8 0x00007ffff4512de4 in g_main_context_dispatch ()
   from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#9 0x00007ffff4513028 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#10 0x00007ffff45130cc in g_main_context_iteration ()
   from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#11 0x00007ffff5ef06bc in QEventDispatcherGlib::processEvents(QFlags<QEventLoop:---Type <return> to continue, or q <return> to quit---
:ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#12 0x00007ffff5e978eb in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#13 0x00007ffff5e9ef46 in QCoreApplication::exec() ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#14 0x0000000000404301 in ?? ()
#15 0x00007ffff521cec5 in __libc_start_main (main=0x403aa0, argc=2,
    argv=0x7fffffffddf8, init=<optimized out>, fini=<optimized out>,
    rtld_fini=<optimized out>, stack_end=0x7fffffffdde8) at libc-start.c:287
#16 0x0000000000406800 in ??