I\'ve searched high and low for this and can easily reproduce it. Running absolute latest PHP SDK and the JS is coming directly from facebook over an HTTPS connection. My \'
The problem is not the ff or the fb plugin is the firebug. I checked A page with ff 8.0 and firebug 1.84 and got the error. Then I checked ff 8.0 with firebug 1.8.3.
This is the compatibility table: Firefox 3.6 with Firebug 1.7.3
Firefox 4.0 with Firebug 1.7.3
Firefox 5.0 with Firebug 1.8.2 (and also Firebug 1.7.3)
Firefox 6.0 with Firebug 1.8.2 (and also Firebug 1.9 alpha)
Firefox 7.0 with Firebug 1.8.2 (and also Firebug 1.9 alpha)
Firefox 8.0 with Firebug 1.8.3 (and also Firebug 1.9 alpha)
Firefox 9.0 with Firebug 1.8.4 (and also Firebug 1.9 alpha)
Firefox 10.0 with Firebug 1.9 alpha
So... don't worry be happy. Is not a real error... I think. :P
It seems like a bug of FireBug :)
steps of reproducing: http://code.google.com/p/fbug/issues/detail?id=4991
reported: https://bugzilla.mozilla.org/show_bug.cgi?id=701029
discussed: http://groups.google.com/group/firebug/browse_thread/thread/2517d5f867b9f526/90f066856b45786f
so take it easy :)