Reference item crashes in export dialog

Observed using smtk:master development build on Ubuntu 16.04

1. Load the pillbox4.gen file in smtk/data/model/3d/genesis. Used the "SMTK importer for Genesis files into smtk::session::vtk::Resource".

2. Using the File ==> Export Simulation menu item, load the attached export_test.py script.

3. In the export dialog, try to select the "Model" item.

Modelbuilder crashes with this message dumped to the console:

terminate called after throwing an instance of 'smtk::common::TypeContainer::BadTypeError'
  what():  Type "shared_ptr<Selection>" not available in this container

Stack trace:

72 0x40f149 /home/john/projects/cmb-master/build/dev-cmb/bin/modelbuilder() [0x40f149] 71 0x7fc10cc8f840 __libc_start_main + 240 70 0x419b40 /home/john/projects/cmb-master/build/dev-cmb/bin/modelbuilder() [0x419b40] 69 0x7fc11617bd30 QCoreApplication::exec() + 128 68 0x7fc1161732ea QEventLoop::exec(QFlags) + 234 67 0x7fc1161cbe3f QEventDispatcherGlib::processEvents(QFlags) + 95 66 0x7fc1047cc49c g_main_context_iteration + 44 65 0x7fc1047cc3f0 /lib/x86_64-linux-gnu/libglib-2.0.so.0(+0x4a3f0) [0x7fc1047cc3f0] 64 0x7fc1047cc197 g_main_context_dispatch + 679 63 0x7fc0e32c6cba /home/john/projects/qt/qt.io/5.12.4/gcc_64/plugins/platforms/../../lib/libQt5XcbQpa.so.5(+0x6bcba) [0x7fc0e32c6cba] 62 0x7fc1167cd76b QWindowSystemInterface::sendWindowSystemEvents(QFlags) + 203 61 0x7fc1167f0125 QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) + 261 60 0x7fc1167eeb73 QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) + 1587 59 0x7fc116174a28 QCoreApplication::notifyInternal2(QObject*, QEvent*) + 264 58 0x7fc11704daa0 QApplication::notify(QObject*, QEvent*) + 688 57 0x7fc1170469ac QApplicationPrivate::notify_helper(QObject*, QEvent*) + 156 56 0x7fc1170a0dbb /home/john/projects/qt/qt.io/5.12.4/gcc_64/lib/libQt5Widgets.so.5(+0x1badbb) [0x7fc1170a0dbb] 55 0x7fc11709e620 /home/john/projects/qt/qt.io/5.12.4/gcc_64/lib/libQt5Widgets.so.5(+0x1b8620) [0x7fc11709e620] 54 0x7fc11704cfba QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer&, bool, bool) + 506 53 0x7fc116174a28 QCoreApplication::notifyInternal2(QObject*, QEvent*) + 264 52 0x7fc11704e07f QApplication::notify(QObject*, QEvent*) + 2191 51 0x7fc1170469ac QApplicationPrivate::notify_helper(QObject*, QEvent*) + 156 50 0x7fc1171b68cb QMenu::event(QEvent*) + 139 49 0x7fc117084790 QWidget::event(QEvent*) + 496 48 0x7fc1171b4380 QMenu::mouseReleaseEvent(QMouseEvent*) + 432 47 0x7fc1171b3476 /home/john/projects/qt/qt.io/5.12.4/gcc_64/lib/libQt5Widgets.so.5(+0x2cd476) [0x7fc1171b3476] 46 0x7fc1171ac35a /home/john/projects/qt/qt.io/5.12.4/gcc_64/lib/libQt5Widgets.so.5(+0x2c635a) [0x7fc1171ac35a] 45 0x7fc117042df0 QAction::activate(QAction::ActionEvent) + 272 44 0x7fc1170409d2 QAction::triggered(bool) + 50 43 0x7fc1161a04e9 QMetaObject::activate(QObject*, int, int, void**) + 1625 42 0x7fc118b2a416 /home/john/projects/cmb-master/build/dev-superbuild/install/lib/libpqApplicationComponents-pv5.8.so.1(+0xe0416) [0x7fc118b2a416] 41 0x7fc0cddc0b17 pqExportSimulationReaction::onTriggered() + 17 40 0x7fc0cddf1fdb pqExportSimulationReaction::exportSimulation() + 2495 39 0x7fc117225c67 QDialog::exec() + 407 38 0x7fc1161732ea QEventLoop::exec(QFlags) + 234 37 0x7fc1161cbe3f QEventDispatcherGlib::processEvents(QFlags) + 95 36 0x7fc1047cc49c g_main_context_iteration + 44 35 0x7fc1047cc3f0 /lib/x86_64-linux-gnu/libglib-2.0.so.0(+0x4a3f0) [0x7fc1047cc3f0] 34 0x7fc1047cc197 g_main_context_dispatch + 679 33 0x7fc0e32c6cba /home/john/projects/qt/qt.io/5.12.4/gcc_64/plugins/platforms/../../lib/libQt5XcbQpa.so.5(+0x6bcba) [0x7fc0e32c6cba] 32 0x7fc1167cd76b QWindowSystemInterface::sendWindowSystemEvents(QFlags) + 203 31 0x7fc1167f0125 QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) + 261 30 0x7fc1167eeb73 QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) + 1587 29 0x7fc116174a28 QCoreApplication::notifyInternal2(QObject*, QEvent*) + 264 28 0x7fc11704daa0 QApplication::notify(QObject*, QEvent*) + 688 27 0x7fc1170469ac QApplicationPrivate::notify_helper(QObject*, QEvent*) + 156 26 0x7fc1170a0dbb /home/john/projects/qt/qt.io/5.12.4/gcc_64/lib/libQt5Widgets.so.5(+0x1badbb) [0x7fc1170a0dbb] 25 0x7fc11709e620 /home/john/projects/qt/qt.io/5.12.4/gcc_64/lib/libQt5Widgets.so.5(+0x1b8620) [0x7fc11709e620] 24 0x7fc11704cfba QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer&, bool, bool) + 506 23 0x7fc116174a28 QCoreApplication::notifyInternal2(QObject*, QEvent*) + 264 22 0x7fc11704e07f QApplication::notify(QObject*, QEvent*) + 2191 21 0x7fc117046985 QApplicationPrivate::notify_helper(QObject*, QEvent*) + 117 20 0x7fc1161747bd QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) + 141 19 0x7fc11713dd80 QComboBoxPrivateContainer::eventFilter(QObject*, QEvent*) + 896 18 0x7fc11727b2a9 QAbstractItemView::setCurrentIndex(QModelIndex const&) + 153 17 0x7fc1161314ad QItemSelectionModel::setCurrentIndex(QModelIndex const&, QFlags) + 157 16 0x7fc1161312da QItemSelectionModel::currentChanged(QModelIndex const&, QModelIndex const&) + 42 15 0x7fc1161a04e9 QMetaObject::activate(QObject*, int, int, void**) + 1625 14 0x7fc117146dc5 /home/john/projects/qt/qt.io/5.12.4/gcc_64/lib/libQt5Widgets.so.5(+0x260dc5) [0x7fc117146dc5] 13 0x7fc11713f57b /home/john/projects/qt/qt.io/5.12.4/gcc_64/lib/libQt5Widgets.so.5(+0x25957b) [0x7fc11713f57b] 12 0x7fc11713d6d1 QComboBox::highlighted(int) + 49 11 0x7fc1161a04e9 QMetaObject::activate(QObject*, int, int, void**) + 1625 10 0x7fc0d28b343f /home/john/projects/cmb-master/build/dev-smtk/lib/libsmtkQtExt.so(+0x24843f) [0x7fc0d28b343f] 9 0x7fc0d29982c8 smtk::extension::qtReferenceItemComboBox::highlightItem(int) + 128 8 0x7fc0d293e530 smtk::extension::qtUIManager::selection() const + 28 7 0x7fc0d293fce1 std::shared_ptr const& smtk::common::TypeContainer::get >() const + 199 6 0x7fc10d802919 /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x8d919) [0x7fc10d802919] 5 0x7fc10d802701 /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x8d701) [0x7fc10d802701] 4 0x7fc10d8026b6 /usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x8d6b6) [0x7fc10d8026b6] 3 0x7fc10d80484d __gnu_cxx::__verbose_terminate_handler() + 365 2 0x7fc10cca603a abort + 362 1 0x7fc10cca4438 gsignal + 56 0 0x7fc10cca44c0 /lib/x86_64-linux-gnu/libc.so.6(+0x354c0) [0x7fc10cca44c0] ( 23.622s) [paraview ] :0 FATL| Signal: SIGABRT