phpqrcode is an external library that hasn't been updated in 2-3 years. On line 2940 of `externals/phpqrcode/phpqrcode.php`, it simply says `$ret;` which I believe is a bug in phpqrcode.
This task is to look into either updating phpqrcode from upstream (if there's a newer rev available), and to attach the quick work around which is `$ret = null;`.