Set $display_errors = true; in your config.php file.
Done. Please have a look
Does it also happen on unmodified script with unmodified template with nothing in ad boxes?
and I saw the error
It's here:
foreach($rewards as $rW){
$rW *= $rewardMultiplier;
$newRewards[] = $rW;
}
$rewards = $newRewards;
I do not understand that I have to fix
And what the error is exactly?