How to check if interface is binded in ServiceProvider?

I laravel 9 app I use EmailingServiceProvider with conditional binding of EmailingService depending on configuration :

<?php

namespace App\Providers;

use Illuminate\Support\ServiceProvider;

class EmailingServiceProvider extends ServiceProvider
{
    public function register()
    {
        $emailingSupport = config('app.emailing_support');
        if($emailingSupport === 'MailerLiteApi') {
            $this->app->bind('App\Library\Services\EmailingServiceInterface', 'App\Library\Services\EmailingService');
        }
    }

}

class EmailingService is called in controller ok, except cases when I want to comment binding code above : // $this->app->bind

I tried to use example at https://www.php.net/manual/en/reflectionclass.isinstantiable.php as :

...
use App\Library\Services\EmailingServiceInterface;

class AuthorController extends Controller
{

    private AuthorMethodsServiceInterface $authorMethodsService;

    private EmailingServiceInterface $emailingService;

    public function __construct(AuthorMethodsServiceInterface $authorMethodsService /*, EmailingServiceInterface $emailingService*/ )
    {
        parent::__construct();
        $this->authorMethodsService = $authorMethodsService;
//        $this->emailingService = $emailingService; // I had to comment this and declarations above
    } 

        // I expected that $reflectionClass->isInstantiable() would have false value below
        $reflectionClass = new \ReflectionClass('EmailingService');  // Line points at this line
        if  $reflectionClass->isInstantiable()) {
            $this->emailingService = new EmailingService();
            $assignedAuthor = $this->emailingService->method();

But I ggot error":

"message": "Class \"EmailingService\" does not exist",
"exception": "ReflectionException",

How that can be done ?

MODIFIED BLOCK :

That does not work. With lines :

use App\Library\Services\EmailingServiceInterface;

...

    $yourService=new EmailingService();  // Error pointing at this line
    if ($author instanceof \Illuminate\Http\JsonResponse and $yourService  instanceof EmailingServiceInterface) {
        ...

I got error:

  "message": "Class \"App\\Http\\Controllers\\EmailingService\" not found",
    "exception": "Error",

?

Thanks!