Incorrect 2FA code results in PHP Fatal Error

[llamaonaskateboard]

Not sure when this started occurring but entering an incorrect 2FA code results in the Roundcube "Oops... something went wrong!" error page with a PHP Fatal Error logged:

PHP Fatal error:  Uncaught Error: Call to a member function get() on null in /var/www/html/webmail/plugins/twofactor_gauthenticator/twofactor_gauthenticator.php:544
Stack trace:
#0 /var/www/html/webmail/plugins/twofactor_gauthenticator/twofactor_gauthenticator.php(173): twofactor_gauthenticator->__logError()
#1 /var/www/html/webmail/program/lib/Roundcube/rcube_plugin_api.php(496): twofactor_gauthenticator->check_2FAlogin()
#2 /var/www/html/webmail/program/include/rcmail_output_html.php(2131): rcube_plugin_api->exec_hook()
#3 /var/www/html/webmail/program/include/rcmail_output_html.php(711): rcmail_output_html->_write()
#4 /var/www/html/webmail/program/include/rcmail_output_html.php(846): rcmail_output_html->write()
#5 /var/www/html/webmail/program/include/rcmail_output_html.php(660): rcmail_output_html->parse()
#6 /var/www/html/webmail/program/include/rcmail.php(293): rcmail_output_html->send()
#7 /var/www/html/webmail/index.php(272): rcmail->action_handler()
#8 {main}
  thrown in /var/www/html/webmail/plugins/twofactor_gauthenticator/twofactor_gauthenticator.php on line 544

It appears the issue may be simply a missing $rcmail = rcmail::get_instance(); in __logError().

[EpeR1]

Try to add $rcmail = rcmail::get_instance(); to twofactor_gauthenticator.php in line 544.
#216 (comment)
Like:

// log error into $_logs_file directory
  private function __logError()
  {
    $rcmail = rcmail::get_instance();
    $_log_dir = $rcmail->config->get('log_dir');
    file_put_contents($_log_dir.'/'.$this->_logs_file, date("Y-m-d H:i:s")."|".$_SERVER['HTTP_X_FORWARDED_FOR']."|".$_SERVER['REMOTE_ADDR']."\n", FILE_APPEND);
  }