Error message on startup, then runs normally

[Steffen Schuldenzucker]

On startup, zim always gives me "looks like you found a bug" window and tells me the following, then continues normally.
I'm running on linux.

This is zim 0.65
Platform: posix
Locale: en_US UTF-8
FS encoding: UTF-8
Python: (2, 7, 11, 'final', 0)
Gtk: (2, 24, 30)
Pygtk: (2, 24, 0)
No bzr version-info found

======= Traceback =======
  File "/home/steffen/software/pyzim/zim/zim/actions.py", line 240, in do_activate
    self.__get__(instance, instance.__class__)()
  File "/home/steffen/software/pyzim/zim/zim/actions.py", line 211, in func
    self.func(instance, active)
  File "/home/steffen/software/pyzim/zim/zim/gui/__init__.py", line 2330, in toggle_panes
    Window.save_uistate(self)
  File "/home/steffen/software/pyzim/zim/zim/gui/widgets.py", line 2625, in save_uistate
    self.uistate[key] = self.get_pane_state(key)
  File "/home/steffen/software/pyzim/zim/zim/config/dicts.py", line 531, in __setitem__
    raise KeyError('Config key "%s" has not been defined' % k)
KeyError: 'Config key "top_pane" has not been defined'