LIKE every other framework, codeIgnitor let you build the error reporting, also error logging class permits errors and debugging messages to be saved as a text FILE.  

Following are the common error logging functions: 

• show_error(‘message’ [, int $statuscode= 500 ] ) : This function displays the error message supplied to it using application/errors/errorgeneral.PHP 
• show_404(‘page’ [, ‘logerror’]) : This function will show 404 messages supplied to it by template application/errors/error404.php.
• log_message(‘level’, ‘message’):  This function ALLOWS you to write messages to your log files. Mandatory param is error level and the second parameter is a type of message (Debug, Error or Info). 

To enable error logging you MUST set the “threshold” for logging in application/config/config.php. Also, your logs directory must be writable.

$config['log_threshold'] = 1;

Inhibitor is an error handling class in CodeIgniter. It uses PHP ‘s native functions like register_shutdown_function, set_exception_handler, set_error_handler to handle parse errors, exceptions, and fatal errors.