Pub Quiz no.2

Error message

• Warning: Invalid argument supplied for foreach() in element_children() (line 6658 of /home/esnup/web/esn.upol.cz/public_html/includes/common.inc).
• Warning: Illegal string offset '#children' in drupal_render() (line 6115 of /home/esnup/web/esn.upol.cz/public_html/includes/common.inc).
• Warning: Cannot assign an empty string to a string offset in drupal_render() (line 6115 of /home/esnup/web/esn.upol.cz/public_html/includes/common.inc).
• Warning: Illegal string offset '#children' in drupal_render() (line 6125 of /home/esnup/web/esn.upol.cz/public_html/includes/common.inc).
• Warning: Illegal string offset '#children' in drupal_render() (line 6163 of /home/esnup/web/esn.upol.cz/public_html/includes/common.inc).
• Warning: Illegal string offset '#printed' in drupal_render() (line 6170 of /home/esnup/web/esn.upol.cz/public_html/includes/common.inc).
• Warning: Invalid argument supplied for foreach() in element_children() (line 6658 of /home/esnup/web/esn.upol.cz/public_html/includes/common.inc).
• Warning: Illegal string offset '#children' in drupal_render() (line 6115 of /home/esnup/web/esn.upol.cz/public_html/includes/common.inc).
• Warning: Cannot assign an empty string to a string offset in drupal_render() (line 6115 of /home/esnup/web/esn.upol.cz/public_html/includes/common.inc).
• Warning: Illegal string offset '#children' in drupal_render() (line 6125 of /home/esnup/web/esn.upol.cz/public_html/includes/common.inc).
• Warning: Illegal string offset '#children' in drupal_render() (line 6163 of /home/esnup/web/esn.upol.cz/public_html/includes/common.inc).
• Warning: Illegal string offset '#printed' in drupal_render() (line 6170 of /home/esnup/web/esn.upol.cz/public_html/includes/common.inc).