Log validation errors even when not shown on screen

// originally https://gist.github.com/richardvav/7961308
// Usage: add to your theme's functions.php file
// log field validation errors
add_filter('gform_validation', 'log_validation_failure');
function log_validation_failure($validation_result){
    $form = $validation_result["form"];
    foreach($form["fields"] as &$field){
        if( $field["failed_validation"] )
            GFCommon::log_error("form #{$form["id"]}: validate() - failed: {$field["label"]}({$field["id"]} - {$field["type"]}) - message: {$field["validation_message"]}");
    }
    return $validation_result;
}