Fatal error: Cannot use object of type stdClass as array

I don't know if this issue of activity module or usercomment module, but after enabling the last and trying to delete a comment as a user (blog author) it first gives this error:

Fatal error: Cannot use object of type stdClass as array in /home/mysite/public_html/sites/all/modules/activity/contrib/commentactivity/commentactivity.module on line 89

If I refresh the page it gives:

    * warning: Invalid argument supplied for foreach() in /home/mysite/public_html/modules/node/node.module on line 521.
    * warning: implode() [function.implode]: Invalid arguments passed in /home/mysite/public_html/modules/node/node.module on line 525.
    * user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1 query: SELECT n.nid, n.vid, n.type, n.status, n.created, n.changed, n.comment, n.promote, n.sticky, r.timestamp AS revision_timestamp, r.title, r.body, r.teaser, r.log, r.format, u.uid, u.name, u.picture, u.data FROM blog_node n INNER JOIN users u ON u.uid = n.uid INNER JOIN blog_node_revisions r ON r.vid = n.vid WHERE in /home/mysite/public_html/includes/database.mysql.inc on line 172.
    * warning: Invalid argument supplied for foreach() in /home/mysite/public_html/modules/node/node.module on line 521.
    * warning: implode() [function.implode]: Invalid arguments passed in /home/mysite/public_html/modules/node/node.module on line 525.
    * user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1 query: SELECT n.nid, n.vid, n.type, n.status, n.created, n.changed, n.comment, n.promote, n.sticky, r.timestamp AS revision_timestamp, r.title, r.body, r.teaser, r.log, r.format, u.uid, u.name, u.picture, u.data FROM blog_node n INNER JOIN users u ON u.uid = n.uid INNER JOIN blog_node_revisions r ON r.vid = n.vid WHERE in /home/mysite/public_html/includes/database.mysql.inc on line 172.

As a result comment is deleted, but not together with its subcomments (replies to that specific comment).