src/MessageBus/PublishesUnhandledMessages.php
public function handle($message, callable $next)
    {
        try {
            $next($message);
        } catch (UndefinedCallable $exception) {
            $this->logger->log(
                $this->logLevel,
                'No message handler found, trying to handle it asynchronously',
                [
                    'type' => get_class($message)
                ]
            );

            $this->publisher->publish($message);
        }
    }
public function handle($message, callable $next)
    {
        try {
            $next($message);
        } catch (UndefinedCallable $exception) {
            $this->logger->log(
                $this->logLevel,
                'No message handler found, trying to handle it asynchronously',
                [
                    'type' => get_class($message)
                ]
            );

            $this->publisher->publish($message);
        }
    }
Handle the message by letting the next middleware handle it. If no handler is defined for this message, then
it is published to be processed asynchronously

@param object $message
@param callable $next