PHP 5.5 Illegal string offset warnings

[sergiitk]

Warning: Invalid argument supplied for foreach() in element_children() (line 6487 of /var/www/dev.dosomething.org/html/includes/common.inc).
Warning: Illegal string offset '#children' in drupal_render() (line 5952 of /var/www/dev.dosomething.org/html/includes/common.inc).
Warning: Illegal string offset '#children' in drupal_render() (line 5962 of /var/www/dev.dosomething.org/html/includes/common.inc).
Warning: Illegal string offset '#children' in drupal_render() (line 6000 of /var/www/dev.dosomething.org/html/includes/common.inc).
Warning: Illegal string offset '#printed' in drupal_render() (line 6007 of /var/www/dev.dosomething.org/html/includes/common.inc).
DoSomething.org

[sergiitk]

As discovered, warnings are reproduced by rendering page_bottom template.
Tested by commenting

$variables['page_bottom'] = drupal_render($variables['page']['page_bottom']);

in template_process_html().

[sergiitk]

Looks like this happens when $page['page_bottom'] is overridden manually in paraneue_dosomething_page_alter().
CC @DFurnes