Code review comment for lp:~and471/inkscape/gallery

Clicking on 'Import' without having an image selected, cause inkscape to crash:

(inkscape:41180): Gtk-CRITICAL **: gtk_list_store_get_value: assertion `VALID_ITER (iter, list_store)' failed

(inkscape:41180): GLib-GObject-CRITICAL **: g_value_get_object: assertion `G_VALUE_HOLDS_OBJECT (value)' failed

(inkscape:41180): GLib-GObject-CRITICAL **: g_value_unset: assertion `G_IS_VALUE (value)' failed

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_PROTECTION_FAILURE at address: 0x00000000
0x0157b125 in Gio::File::get_path ()
(gdb) bt
#0 0x0157b125 in Gio::File::get_path ()
#1 0x0053e4ac in Inkscape::UI::Dialog::Gallery::on_button_import_clicked (this=0x3f03200) at ui/dialog/gallery.cpp:237
#2 0x0167f08a in Glib::SignalProxyNormal::slot0_void_callback ()
#3 0x03390f39 in g_closure_invoke ()
#4 0x033a3425 in signal_emit_unlocked_R ()
#5 0x033a4741 in g_signal_emit_valist ()
#6 0x033a4a49 in g_signal_emit ()
#7 0x0175c14a in gtk_button_clicked ()
#8 0x0175e2f8 in gtk_real_button_released ()
#9 0x03390f39 in g_closure_invoke ()
#10 0x033a2d28 in signal_emit_unlocked_R ()
#11 0x033a4741 in g_signal_emit_valist ()
#12 0x033a4a49 in g_signal_emit ()
#13 0x0175c0aa in gtk_button_released ()
#14 0x0175d38b in gtk_button_button_release ()
#15 0x0181685b in _gtk_marshal_BOOLEAN__BOXED ()
#16 0x03390f39 in g_closure_invoke ()
#17 0x033a3238 in signal_emit_unlocked_R ()
#18 0x033a4487 in g_signal_emit_valist ()
#19 0x033a4a49 in g_signal_emit ()
#20 0x01945546 in gtk_widget_event_internal ()
#21 0x01814a58 in gtk_propagate_event ()
#22 0x01814fcd in gtk_main_do_event ()
#23 0x0280f845 in gdk_event_dispatch ()
#24 0x0344c71d in g_main_context_dispatch ()
#25 0x034505ab in g_main_context_iterate ()
#26 0x03450887 in g_main_loop_run ()
#27 0x01813fa1 in gtk_main ()
#28 0x011ca59b in Gtk::Main::run ()
#29 0x0000539c in ~vector [inlined] () at stl_vector.h:986
#30 sp_main_gui (argc=1, argv=0xbffff2d0) at main.cpp:993
#31 0x00003f96 in start ()
(gdb)