When I run the following code, I get segmentation fault.

<code>
>>> from gi.repository import Gtk
>>> Gtk.TreeView().get_style_context().get_color(Gtk.StateFlags.INSENSITIVE)

(.:11732): Gtk-CRITICAL **: gtk_style_context_get_property: assertion `priv->widget != NULL || priv->widget_path != NULL' failed
/usr/lib/python3/dist-packages/gi/types.py:47: Warning: /build/buildd/glib2.0-2.34.0/./gobject/gtype.c:4204: type id `0' is invalid
  return info.invoke(*args, **kwargs)
/usr/lib/python3/dist-packages/gi/types.py:47: Warning: can't peek value table for type `<invalid>' which is not currently referenced
  return info.invoke(*args, **kwargs)
Segmentation fault
</code>

As I found out on #python channel that I should split the constructor and getter in the following way:

<code>
>>> from gi.repository import Gtk
>>> tv = Gtk.TreeView()
>>> tv.get_style_context().get_color(Gtk.StateFlags.INSENSITIVE)
<Gdk.Color(red=0.585613, green=0.567059, blue=0.548504, alpha=1.000000)>
</code>

It would be nicer to raise a python exception instead of a segfault.