I get the sanme error when I load the “Presentation-sidebar widgets” menu. In my case it doesn’t go away by itself (so far). At the same time clicking on the configuration icon on a widget works flaky, sometimes it brings a submenu, sometimes I need to click several times before I get that menu. Sometimes, even if I clicked only once, the menu apears two times…
Not a big deal since it works on the site, just anoying.
