To reproduce. Launch, right click in ruler area then drag down
until over the master track and let go.
#0 0x0000555555ba1d44 in boost::shared_ptr<ARDOUR::Route>::get() const (this=0x8) at /usr/include/boost/smart_ptr/shared_ptr.hpp:748
#1 0x0000555555ba0a2f in boost::dynamic_pointer_cast<ARDOUR::Track, ARDOUR::Route>(boost::shared_ptr<ARDOUR::Route> const&) (r=...)
at /usr/include/boost/smart_ptr/shared_ptr.hpp:904
#2 0x000055555650b92b in RouteUI::track() const (this=0x0) at ../gtk2_ardour/route_ui.cc:1885
#3 0x0000555555d0b92f in Editor::popup_track_context_menu(int, int, ItemType, bool) (this=
0x555557a3efd0, button=1, time=600214966, item_type=StreamItem, with_selection=false) at ../gtk2_ardour/editor.cc:1595
#4 0x0000555555e1a4cf in Editor::button_release_handler(ArdourCanvas::Item*, _GdkEvent*, ItemType) (this=0x555557a3efd0, item=
0x555557b2fe00, event=0x7fffffffc310, item_type=StreamItem) at ../gtk2_ardour/editor_mouse.cc:1543
....
