I added "Remove placemark" but didn't add any placemark. After it I added "Wait" and started the tour. Marble crashed.

Reproducible: Always

Steps to Reproduce:
1. Go to "Tour" panel. (Settings->Panels->Tour)
2. Create a new tour.
3. Add "Remove placemark" item.
4. Add a delay. (tour won't start without it)

Actual Results:  
Marble crashed


Backtrace:
#0  0x00007ffff57acd27 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1  0x00007ffff57ae418 in __GI_abort () at abort.c:89
#2  0x00007ffff7967c22 in qt_message_output (msgType=msgType@entry=QtFatalMsg, 
    buf=0x12ddf68 "ASSERT: \"!\"Didn't find target row.\"\" in file /home/sergobot/marble/sources/src/lib/marble/kdescendantsproxymodel.cpp, line 412") at global/qglobal.cpp:2386
#3  0x00007ffff7967f89 in qt_message(QtMsgType, const char *, typedef __va_list_tag __va_list_tag *) (msgType=msgType@entry=QtFatalMsg, 
    msg=msg@entry=0x7ffff7ad38c0 "ASSERT: \"%s\" in file %s, line %d", ap=ap@entry=0x7fffffffb6a8) at global/qglobal.cpp:2432
#4  0x00007ffff7968794 in qFatal (msg=msg@entry=0x7ffff7ad38c0 "ASSERT: \"%s\" in file %s, line %d") at global/qglobal.cpp:2615
#5  0x00007ffff79687d6 in qt_assert (assertion=assertion@entry=0x7ffff6892645 "!\"Didn't find target row.\"", 
    file=file@entry=0x7ffff68922c8 "/home/sergobot/marble/sources/src/lib/marble/kdescendantsproxymodel.cpp", line=line@entry=412) at global/qglobal.cpp:2060
#6  0x00007ffff66d1c18 in KDescendantsProxyModel::mapToSource (this=<optimized out>, proxyIndex=...) at /home/sergobot/marble/sources/src/lib/marble/kdescendantsproxymodel.cpp:412
#7  0x00007ffff66d1fa1 in KDescendantsProxyModel::data (this=0x7adc98, index=..., role=42) at /home/sergobot/marble/sources/src/lib/marble/kdescendantsproxymodel.cpp:495
#8  0x00007ffff737ff78 in QSortFilterProxyModel::data (this=<optimized out>, index=..., role=42) at itemviews/qsortfilterproxymodel.cpp:1735
#9  0x00007ffff737d17f in QSortFilterProxyModel::lessThan (this=<optimized out>, left=..., right=...) at itemviews/qsortfilterproxymodel.cpp:2420
#10 0x00007ffff737e1a6 in QSortFilterProxyModelPrivate::proxy_intervals_for_source_items_to_add (this=this@entry=0xbfdce0, proxy_to_source=..., source_items=..., 
    source_parent=..., orient=orient@entry=Qt::Vertical) at itemviews/qsortfilterproxymodel.cpp:614
#11 0x00007ffff7382a2f in QSortFilterProxyModelPrivate::insert_source_items (this=this@entry=0xbfdce0, source_to_proxy=..., proxy_to_source=..., source_items=..., 
    source_parent=..., orient=orient@entry=Qt::Vertical, emit_signal=true) at itemviews/qsortfilterproxymodel.cpp:672
#12 0x00007ffff738309e in QSortFilterProxyModelPrivate::source_items_inserted (this=this@entry=0xbfdce0, source_parent=..., start=<optimized out>, end=<optimized out>, 
    orient=orient@entry=Qt::Vertical) at itemviews/qsortfilterproxymodel.cpp:806
#13 0x00007ffff738333f in QSortFilterProxyModelPrivate::_q_sourceRowsInserted (this=0xbfdce0, source_parent=..., start=<optimized out>, end=<optimized out>)
    at itemviews/qsortfilterproxymodel.cpp:1297
#14 0x00007ffff7a86a7a in QMetaObject::activate (sender=sender@entry=0x7adcb0, m=m@entry=0x7ffff7dd6860 <QAbstractItemModel::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=5, argv=argv@entry=0x7fffffffbe30) at kernel/qobject.cpp:3567
#15 0x00007ffff7ad0404 in QAbstractItemModel::rowsInserted (this=this@entry=0x7adcb0, _t1=..., _t2=1858, _t3=1904) at .moc/release-shared/moc_qabstractitemmodel.cpp:196
#16 0x00007ffff7a6c062 in QAbstractItemModel::endInsertRows (this=0x7adcb0) at kernel/qabstractitemmodel.cpp:2433
#17 0x00007ffff7382ce5 in QSortFilterProxyModelPrivate::insert_source_items (this=this@entry=0x7ac3c0, source_to_proxy=..., proxy_to_source=..., source_items=..., 
    source_parent=..., orient=orient@entry=Qt::Vertical, emit_signal=true) at itemviews/qsortfilterproxymodel.cpp:695
#18 0x00007ffff738309e in QSortFilterProxyModelPrivate::source_items_inserted (this=this@entry=0x7ac3c0, source_parent=..., start=<optimized out>, end=<optimized out>, 
    orient=orient@entry=Qt::Vertical) at itemviews/qsortfilterproxymodel.cpp:806
#19 0x00007ffff738333f in QSortFilterProxyModelPrivate::_q_sourceRowsInserted (this=0x7ac3c0, source_parent=..., start=<optimized out>, end=<optimized out>)
    at itemviews/qsortfilterproxymodel.cpp:1297
#20 0x00007ffff7a86a7a in QMetaObject::activate (sender=sender@entry=0x7adc98, m=m@entry=0x7ffff7dd6860 <QAbstractItemModel::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=5, argv=argv@entry=0x7fffffffc170) at kernel/qobject.cpp:3567
#21 0x00007ffff7ad0404 in QAbstractItemModel::rowsInserted (this=this@entry=0x7adc98, _t1=..., _t2=1913, _t3=1959) at .moc/release-shared/moc_qabstractitemmodel.cpp:196
#22 0x00007ffff7a6c062 in QAbstractItemModel::endInsertRows (this=this@entry=0x7adc98) at kernel/qabstractitemmodel.cpp:2433
#23 0x00007ffff66d4b48 in KDescendantsProxyModelPrivate::processPendingParents (this=this@entry=0x7b80a0)
    at /home/sergobot/marble/sources/src/lib/marble/kdescendantsproxymodel.cpp:162
#24 0x00007ffff66d453e in KDescendantsProxyModelPrivate::processPendingParents (this=this@entry=0x7b80a0)
    at /home/sergobot/marble/sources/src/lib/marble/kdescendantsproxymodel.cpp:178
#25 0x00007ffff66d5ad5 in KDescendantsProxyModelPrivate::scheduleProcessPendingParents (this=this@entry=0x7b80a0)
    at /home/sergobot/marble/sources/src/lib/marble/kdescendantsproxymodel.cpp:115
#26 0x00007ffff66d5ea2 in KDescendantsProxyModelPrivate::sourceRowsInserted (this=0x7b80a0, parent=..., start=<optimized out>, end=23)
    at /home/sergobot/marble/sources/src/lib/marble/kdescendantsproxymodel.cpp:686
#27 0x00007ffff7a86a7a in QMetaObject::activate (sender=sender@entry=0x7adc80, m=m@entry=0x7ffff7dd6860 <QAbstractItemModel::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=5, argv=argv@entry=0x7fffffffc800) at kernel/qobject.cpp:3567
#28 0x00007ffff7ad0404 in QAbstractItemModel::rowsInserted (this=this@entry=0x7adc80, _t1=..., _t2=23, _t3=23) at .moc/release-shared/moc_qabstractitemmodel.cpp:196
#29 0x00007ffff7a6c062 in QAbstractItemModel::endInsertRows (this=this@entry=0x7adc80) at kernel/qabstractitemmodel.cpp:2433
#30 0x00007ffff66cd224 in Marble::GeoDataTreeModel::addFeature (this=this@entry=0x7adc80, parent=0x7d0da8, feature=0x7d0da8, row=23)
    at /home/sergobot/marble/sources/src/lib/marble/GeoDataTreeModel.cpp:807
#31 0x00007ffff66cdadf in Marble::GeoDataTreeModel::qt_static_metacall (_o=0x7adc80, _c=<optimized out>, _id=3, _a=0x7fffffffca60)
    at /home/sergobot/marble/build/src/lib/marble/GeoDataTreeModel.moc:89
#32 0x00007ffff7a86a7a in QMetaObject::activate (sender=0xedf970, m=m@entry=0x7ffff6c11680 <Marble::TourPlayback::staticMetaObject>, local_signal_index=local_signal_index@entry=5, 
    argv=argv@entry=0x7fffffffca60) at kernel/qobject.cpp:3567
#33 0x00007ffff669ea9f in Marble::TourPlayback::added (this=<optimized out>, _t1=0x7d0da8, _t2=0x7d0da8, _t3=-1) at /home/sergobot/marble/build/src/lib/marble/TourPlayback.moc:163
#34 0x00007ffff7a86a7a in QMetaObject::activate (sender=0x12745e0, m=m@entry=0x7ffff6c120c0 <Marble::AnimatedUpdateTrack::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=3, argv=argv@entry=0x7fffffffcbb0) at kernel/qobject.cpp:3567
#35 0x00007ffff66a66ef in Marble::AnimatedUpdateTrack::added (this=<optimized out>, _t1=0x7d0da8, _t2=0x7d0da8, _t3=-1)
    at /home/sergobot/marble/build/src/lib/marble/AnimatedUpdateTrack.moc:134
#36 0x00007ffff7a86a7a in QMetaObject::activate (sender=sender@entry=0x12ab400, m=m@entry=0x7ffff6c119a0 <Marble::PlaybackItem::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=7, argv=argv@entry=0x7fffffffcd00) at kernel/qobject.cpp:3567
#37 0x00007ffff66a14df in Marble::PlaybackItem::added (this=this@entry=0x12ab400, _t1=_t1@entry=0x7d0da8, _t2=_t2@entry=0x7d0da8, _t3=_t3@entry=-1)
    at /home/sergobot/marble/build/src/lib/marble/PlaybackItem.moc:166
#38 0x00007ffff66a22c1 in Marble::PlaybackAnimatedUpdateItem::stop (this=0x12ab400) at /home/sergobot/marble/sources/src/lib/marble/PlaybackAnimatedUpdateItem.cpp:194
#39 0x00007ffff66a651a in Marble::AnimatedUpdateTrack::stop (this=0x12745e0) at /home/sergobot/marble/sources/src/lib/marble/AnimatedUpdateTrack.cpp:100
#40 0x00007ffff669ecb0 in Marble::TourPlayback::stopTour (this=0xedf970) at /home/sergobot/marble/sources/src/lib/marble/TourPlayback.cpp:97
#41 0x00007ffff7a86a7a in QMetaObject::activate (sender=0xedfa80, m=<optimized out>, local_signal_index=<optimized out>, argv=0x0) at kernel/qobject.cpp:3567
#42 0x00007ffff7a86a7a in QMetaObject::activate (sender=sender@entry=0x126e160, m=m@entry=0x7ffff6c119a0 <Marble::PlaybackItem::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x0) at kernel/qobject.cpp:3567
#43 0x00007ffff66a12d0 in Marble::PlaybackItem::finished (this=this@entry=0x126e160) at /home/sergobot/marble/build/src/lib/marble/PlaybackItem.moc:119
#44 0x00007ffff66a3dc6 in Marble::PlaybackWaitItem::playNext (this=0x126e160) at /home/sergobot/marble/sources/src/lib/marble/PlaybackWaitItem.cpp:63
#45 0x00007ffff7a86a7a in QMetaObject::activate (sender=sender@entry=0x1273750, m=m@entry=0x7ffff7dd4540 <QSingleShotTimer::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x0) at kernel/qobject.cpp:3567
#46 0x00007ffff7a8f82a in timeout (this=0x1273750) at .moc/release-shared/qtimer.moc:96
#47 QSingleShotTimer::timerEvent (this=0x1273750) at kernel/qtimer.cpp:317
#48 0x00007ffff7a8ae0b in QObject::event (this=0x1273750, e=<optimized out>) at kernel/qobject.cpp:1253
#49 0x00007ffff6dff11c in QApplicationPrivate::notify_helper (this=this@entry=0x6c0170, receiver=receiver@entry=0x1273750, e=e@entry=0x7fffffffd410) at kernel/qapplication.cpp:4570
#50 0x00007ffff6e05870 in QApplication::notify (this=0x7fffffffdb80, receiver=0x1273750, e=0x7fffffffd410) at kernel/qapplication.cpp:4356
#51 0x00007ffff7a7286d in QCoreApplication::notifyInternal (this=0x7fffffffdb80, receiver=0x1273750, event=event@entry=0x7fffffffd410) at kernel/qcoreapplication.cpp:953
#52 0x00007ffff7aa24eb in sendEvent (event=0x7fffffffd410, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:231
#53 QTimerInfoList::activateTimers (this=0x6b9d80) at kernel/qeventdispatcher_unix.cpp:621
#54 0x00007ffff7a9f749 in timerSourceDispatch (source=<optimized out>) at kernel/qeventdispatcher_glib.cpp:193
#55 idleTimerSourceDispatch (source=<optimized out>) at kernel/qeventdispatcher_glib.cpp:240
#56 0x00007ffff4e75c5d in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#57 0x00007ffff4e75f48 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#58 0x00007ffff4e75ffc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#59 0x00007ffff7aa0031 in QEventDispatcherGlib::processEvents (this=0x6bc3c0, flags=...) at kernel/qeventdispatcher_glib.cpp:434
#60 0x00007ffff6ea24e6 in QGuiEventDispatcherGlib::processEvents (this=<optimized out>, flags=...) at kernel/qguieventdispatcher_glib.cpp:204
#61 0x00007ffff7a714f1 in QEventLoop::processEvents (this=this@entry=0x7fffffffd690, flags=...) at kernel/qeventloop.cpp:149
#62 0x00007ffff7a71805 in QEventLoop::exec (this=this@entry=0x7fffffffd690, flags=...) at kernel/qeventloop.cpp:204
#63 0x00007ffff7a76f67 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1225
#64 0x0000000000425949 in main (argc=2, argv=0x7fffffffdd38) at /home/sergobot/marble/sources/src/apps/marble-qt/qtmain.cpp:258