The error log at `/data/project/wikiviewstats/error.log` is growing constantly and has reached 25 GByte now. It is filled with entries like:
```
PHP Notice: Undefined variable: prid in /data/project/wikiviewstats/wvs_modules/Core.php on line 994
PHP Stack trace:
PHP 1. {main}() /data/project/wikiviewstats/public_html/api.php:0
PHP 2. wvs::get_stats_day() /data/project/wikiviewstats/public_html/api.php:85
```
and:
```
PHP Warning: Cannot modify header information - headers already sent by (output started at /data/project/wikiviewstats/wvs_modules/Core.php:994) in /data/project/wikiviewstats/public_html/api.php on line 210
PHP Stack trace:
PHP 1. {main}() /data/project/wikiviewstats/public_html/api.php:0
PHP 2. header() /data/project/wikiviewstats/public_html/api.php:210
```
Unfortunately, I don't understand the code well enough to fix this.