How can I solve ErrorExceptionIlluminate\Notifications\SendQueuedNotifications on laravel?

If I executed my notification on production server, there exist error like this :

ErrorExceptionIlluminate\Notifications\SendQueuedNotifications preg_split() expects parameter 2 to be string, array given

I check the error using https://app.bugsnag.com

The full error like this :

On my localhost and my staging server it's no error

It's just error in production server

My notification like this :

<?php
namespace App\Notifications;
use Illuminate\Bus\Queueable;
use Illuminate\Contracts\Broadcasting\ShouldBroadcast;
use Illuminate\Notifications\Notification;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Notifications\Messages\MailMessage;
class CheckoutOrder extends Notification implements ShouldQueue, ShouldBroadcast
{
    use Queueable;
    private $data;
    public function __construct($data)
    {
        $this->data = $data;
    }
    public function via($notifiable)
    {
        return ['mail','database','broadcast'];
    }
    public function toMail($notifiable)
    {
        return (new MailMessage)
                    ->subject('test subject')
                    ->view('vendor.notifications.mail.email-checkout-order',['data'=>$this->data, 'name' => $notifiable->name]);
    }
    public function toArray($notifiable)
    {
        return [
            'id'            => $this->data['invoice']->id,
            'time'          => $this->data['invoice']->created_at,
            'group'         => 'purchase',
        ];
    }
}

My env like this :

APP_ENV=production
APP_KEY=secretkey
APP_DEBUG=false
APP_LOG_LEVEL=debug
APP_URL=https://secretapp.co.id

DB_CONNECTION=mysql
DB_HOST=secret
DB_HOST_MONGO=localhost
DB_PORT=3306
DB_DATABASE=secretdb
DB_USERNAME=secretusername
DB_PASSWORD=secretpassword

BROADCAST_DRIVER=pusher
CACHE_DRIVER=redis
SESSION_DRIVER=redis
QUEUE_DRIVER=redis

REDIS_HOST=127.0.0.1
REDIS_PASSWORD=null
REDIS_PORT=6379

MAIL_DRIVER=smtp
MAIL_HOST=smtp.gmail.com
MAIL_PORT=587
MAIL_USERNAME=secret@gmail.com
MAIL_PASSWORD=secret
MAIL_ENCRYPTION=tls

How can I solve this problem?

via Chebli Mohamed