PHP Warning: array_merge()

Hello
I am receiving the following error in my error log produced by SNAP;

PHP Warning: array_merge() [function.array-merge]: Argument #1 is not an array in XXX/wp-content/plugins/social-networks-auto-poster-facebook-twitter-g/NextScripts_SNAP.php on line 689

The error seems to be produced every 20 minutes and is generating very large error logs, whilst everything seems to function correctly in the admin area

http://wordpress.org/extend/plugins/social-networks-auto-poster-facebook-twitter-g/