PusherBroadcaster error. Laravel 6 - How to Fix? - php

Question

I have Laravel 6 and use pusher as a broadcast event. But I get this error (see screenshot)
the error
\Illuminate\Broadcasting\Broadcasters\PusherBroadcaster.php:121
screenshot stacktrace error
here is my controller:
public function sendMessage(Request $request)
{
//validate incoming request
$this->validate($request, [
'message' => 'required|string'
]);
try {
$iam = Auth::user();
$message = $iam->family->messages()->create([
'message' => $request->input('message'),
'id_user' => $iam->id
]);
event(new ChatSubmitted('$message'));
//return successful response
return response()->json(['messages' => $request->all(), 'message' => 'Send Message Succesfully'], 200);
} catch (\Exception $e) {dd($e);
//return error message
return response()->json(['message' => 'Send Message Failed!'], 409);
}
}
and here is my event:
class ChatSubmitted implements ShouldBroadcast
{
use Dispatchable, InteractsWithSockets, SerializesModels;
public $message;
/**
* Create a new event instance.
*
* #return void
*/
public function __construct($message)
{
$this->message = $message;
}
/**
* Get the channels the event should broadcast on.
*
* #return \Illuminate\Broadcasting\Channel|array
*/
public function broadcastOn()
{
return new Channel('my-channel');
}
}
the routes of api:
Route::get('messages', 'ChatsController#fetchMessages');
Route::post('messages/create', 'ChatsController#sendMessage');