Facebook posting throwing an error?

I get this error on my site (rvawish.es) when I sign in with Facebook and post a comment with “also post to Facebook” checked:

Warning: Illegal string offset 'facebook' in /home/punchprod/webapps/rvawishes/wp-content/plugins/social/lib/social/service/facebook.php on line 113

Warning: array_shift() expects parameter 1 to be array, null given in /home/punchprod/webapps/rvawishes/wp-content/plugins/social/lib/social/service/facebook.php on line 114

Warning: Cannot modify header information - headers already sent by (output started at /home/punchprod/webapps/rvawishes/wp-content/plugins/social/lib/social/service/facebook.php:113) in /home/punchprod/webapps/rvawishes/wp-includes/pluggable.php on line 896

It doesn’t happen when I just post the comment without “also post to Facebook” checked, and it doesn’t happen when I sign in with Twitter.

Any idea what’s happening here?

http://ww.wp.xz.cn/plugins/social/