Theme Hook "" Not found Watchdog error on Custom Theme

Hello everyone.

Hope you can help shed some light on an Issue we are having with a custom theme written by another developer that is currently unavailable...?

Our site's watchdog is reporting a "Theme hook not found." (note the double space in the sentence there)

Upon investigation I found that the core theme() function (/include/theme.inc) is writing this watchdog entry, with a token replace of array('%hook' => $hook)

This watchdog entry is getting triggered on every page load, no matter if the user is logged in or not.

I believe that the issue is to do with code in the template.php file.

The template has a function _node_theme_hook_suggestions() that builds up the $variables['theme_hook_suggestions'][] array in the following format and returns an array as follows:

return array(
    117 => 'page__jurisdictions',
    621 => 'page__branch_chapters',
    etc...
);

as well as other sub functions that build up the $variables array in the following format:

$variables['theme_hook_suggestions'][] = $theme;

Could someone point me in the right direction of the correct way to pass the suggested hooks to the theme registry as I think that as the %hook token is showing blank there may be an issue with the array passed?

Any pointers would be greatly appreciated.

thanks