Lots of warnings (PHP 7.2.27-1+0~20200123.34+debian9~1.gbp63c0bc)

[Wally73]

[24-Jan-2020 18:13:43 Europe/Amsterdam] PHP Warning: Use of undefined constant sortingFunction - assumed 'sortingFunction' (this will throw an Error in a future version of PHP) in /var/www/vnstat/app/includes/vnstat.php on line 136
[24-Jan-2020 18:13:43 Europe/Amsterdam] PHP Notice: Undefined variable: i in /var/www/vnstat/app/includes/vnstat.php on line 162
[24-Jan-2020 18:13:43 Europe/Amsterdam] PHP Notice: Undefined variable: i in /var/www/vnstat/app/includes/vnstat.php on line 188
[24-Jan-2020 18:13:43 Europe/Amsterdam] PHP Notice: Undefined variable: i in /var/www/vnstat/app/includes/vnstat.php on line 104
[24-Jan-2020 18:13:43 Europe/Amsterdam] PHP Notice: Undefined variable: i in /var/www/vnstat/app/includes/vnstat.php on line 141
[24-Jan-2020 18:13:43 Europe/Amsterdam] PHP Notice: Undefined variable: i in /var/www/vnstat/app/includes/vnstat.php on line 173
[24-Jan-2020 18:13:43 Europe/Amsterdam] PHP Notice: Undefined variable: i in /var/www/vnstat/app/includes/vnstat.php on line 199