On the early stage of upgrading geeklog version of a website, it needs debugs.
When I tested debugging version 1.4.1, the geeklog's error handling process seemed disturb my debugging.
It seems cancel php-core's error handling.
For instance, browsers frequently shows just "Unfortunately, an error has occurred rendering this page. Please try again", without issuing any php error logs in system and any errors on browsers.
But when I commented out the lines in lib-common:if( function_exists('set_error_handler'

){},
then browser start to display errors and it is also logged.
Also, switching $_COM_VERBOSE to true or false, it seems not change error handling on the early stage of debugging.
Question is, on the latest geeklog, would same thing happen? or manner of debugging is changed?
Yes the current version of Geeklog 2.1.3 will modify the error handling in pretty much the same spot.
In siteconfig.php you can enable
$_CONF['rootdebug'] = true;
which will turn on the debug trace which can be pretty helpful at times.