There are multiple ways of how you can handle errors produces by PHP workers.
The simplest and most common way would be responding to parent service with the error message using getWorker()->error():
try {
$resp = new \Zend\Diactoros\Response();
$resp->getBody()->write("hello world");
$psr7->respond($resp);
} catch (\Throwable $e) {
$psr7->getWorker()->error((string)$e);
}
You can also flush your warning and errors into error_log or STDERR to output them directly into the console (similar to docker-compose).
error_log("my message");