Traceback (most recent call last):
  File "/usr/lib/python2.6/atexit.py", line 24, in _run_exitfuncs
    func(*targs, **kargs)
  File "/usr/share/software-center/softwarecenter/app.py", line 569, in save_state
    available_node_expanded = self.view_switcher.is_available_node_expanded()
  File "/usr/share/software-center/softwarecenter/view/viewswitcher.py", line 143, in is_available_node_expanded
    available_path = model.get_path(model.available_iter)
AttributeError: 'NoneType' object has no attribute 'get_path'