loading my model to load_class

Having eliminated CSRF and 404 errors from the set, recipients being in standard config, and knowing that extending/overriding CI_Exceptions won't work, you can use a pre_controller hook to do something like this:

With pre_controller hook custom error handlers aren't called. If I change hook to pre_system, they are called, but there is another error with Email library:

PHP Code:

    protected function _set_error_message($msg, $val = '')
    {
        $CI =& get_instance();
        $CI->lang->load('email');

        if (sscanf($msg, 'lang:%s', $line) !== 1 OR FALSE === ($line = $CI->lang->line($line)))
        {
            $this->_debug_msg[] = str_replace('%s', $val, $msg).'<br />';
        }
        else
        {
            $this->_debug_msg[] = str_replace('%s', $val, $line).'<br />';
        }
    } 


And again, issue with getting CI instance.
This method is called from another Email method _spool_email.

As I understand the error is triggerred in CodeIgniter.php when the system calls load_class('Input', 'core') - before pre_controller hook (I think only pre_system hook can used for this purpose).
And then "Input constructor" -> "Security->csrf_verify" -> "Security->csrf_show_error" (error is cycled).