SeasideFilteredModel crashes if personByRow() is called with -1

[vranki]

Program received signal SIGSEGV, Segmentation fault.
0x69d0738d in QtContacts::QContactId::toString() const () from /usr/lib/libQt5Contacts.so.5
(gdb) bt
#0 0x69d0738d in QtContacts::QContactId::toString() const () from /usr/lib/libQt5Contacts.so.5
#1 0x69c9c0bf in ?? () from /usr/lib/libcontactcache-qt5.so.0
#2 0x69c9c9cc in SeasideCache::itemById(QtContacts::QContactId const&, bool) () from /usr/lib/libcontactcache-qt5.so.0
#3 0x69da7859 in SeasideFilteredModel::personByRow (this=0x50418a30, row=-1) at seasidefilteredmodel.cpp:521
#4 0x69db949c in SeasideFilteredModel::qt_static_metacall (_o=0x50418a30, _c=QMetaObject::InvokeMetaMethod, _id=16, _a=0x77ffdcd0) at moc_seasidefilteredmodel.cpp:273
#5 0x69db999e in SeasideFilteredModel::qt_metacall (this=0x50418a30, _c=QMetaObject::InvokeMetaMethod, id=16, a=0x77ffdcd0) at moc_seasidefilteredmodel.cpp:386
#6 0x6efb757f in QMetaObject::metacall(QObject, QMetaObject::Call, int, void*) () from /usr/lib/libQt5Core.so.5
#7 0x6fa19bb9 in ?? () from /usr/lib/libQt5Qml.so.5

I'll fix this some day when I have time.