Error when updating from 6.x-1.0-beta5 to 6.x-1.x-dev

When upgrading from 6.x-1.0-beta5 to 6.x-1.x-dev I obtained the error:
"array_merge() [function.array-merge]: Argument #2 is not an array in /home/virtual_web/DOMAIN_NAME/public_html/www/update.php on line 174."

However, the module seems to work well after update (the beta5 did not work for me, no results were counted).