instead of hiding all those notices you could also use a foreach with a map..

something along the lines:
```
$propMap = array(
  '@timestamp' => 'datetime',
  '@message' => 'message',
  // ..
);

$message = array();
foreach($propMap  as $logstashProp => $recordProp) {
  $message[$logstashProp] = !empty($record[$recordProp]) ? $record[$recordProp] : '';
}
```