Shell crashes after unlocking screen when using the "native windows placement" extension

[Alessandro Crismani <alessandro crismani gmail com>]

Hi everybody,

I have upgraded to the latest Gnome 3.6. I am experiencing frequent 
crashes of Gnome Shell, which never happened before.

Given that I consider the shell to be very solid, I though that the 
culprit might be some extension, and in fact I can reliably reproduce 
the crash by activating the "native windows placement" extension, 
locking/unlocking the screen (with the new screen locker) and going to 
the overview. Such combination makes the shell crash telling me (in the 
terminal running the shell process):

St-ERROR **: st_widget_get_theme_node called on the widget [0x53d0480 
StWidget.workspaces-view] which is not in the stage.

Is somebody else seeing this? Any idea what is going wrong with that 
extension, given that it doesn't seem to be a JS error?

Cheers,
Alessandro