Why am I not getting a list of all campaigns when using the google-ads-php getCampaigns example library?

I'm trying to get a list of all campaigns using the Google Ads API. To do this, I use an example from the google-ads-php library, but this code does not work for me. What's weird is that the foreach loop doesn't even run and I don't see the output of var_dump. Can anyone suggest me what I'm doing wrong? Or give a link to an example with working code?

My PHP Symfony class code:

    class CheckController extends AbstractController{     /**      * @Route("/check", name="check")      */     public function index(): Response{         $config = $this->getParameter('kernel.project_dir') . '/google_ads_php.ini';         if (!is_file($config)) return $this->json([$config]);         $oAuth2Credential = (new OAuth2TokenBuilder())             ->fromFile($config)             ->build();         $googleAdsClient = (new GoogleAdsClientBuilder())             ->fromFile($config)             ->withOAuth2Credential($oAuth2Credential)             ->build();         try {             self::runExample(                 $googleAdsClient,                 'xxxxxxxxxx'             );         } catch (GoogleAdsException $googleAdsException) {             printf(                 "Request with ID '%s' has failed.%sGoogle Ads failure details:%s",                 $googleAdsException->getRequestId(),                 PHP_EOL,                 PHP_EOL             );             foreach ($googleAdsException->getGoogleAdsFailure()->getErrors() as $error) {                 /** @var GoogleAdsError $error */                 printf(                     "\t%s: %s%s",                     $error->getErrorCode()->getErrorCode(),                     $error->getMessage(),                     PHP_EOL                 );             }             exit(1);         } catch (ApiException $apiException) {             printf(                 "ApiException was thrown with message '%s'.%s",                 $apiException->getMessage(),                 PHP_EOL             );             exit(1);         }         $test = self::runExample($googleAdsClient, '1138211281');         foreach ($test->iterateAllElements() as $googleAdsRow) {             echo '<pre>';                 var_dump($googleAdsRow->getCampaign()->getId());             echo '</pre>';         }         /*echo '<pre>';                 var_dump($test);         echo '</pre>';*/         foreach ($test->iterateAllElements() as $googleAdsRow) {             /** @var GoogleAdsRow $googleAdsRow */             var_dump($googleAdsRow->getCampaign()->getId());         }         /*return $this->render('base.html.twig', [             'test' => $test         ]);*/          return $this->json([              'message' => 'Welcome to your new controller!',              'path' => 'src/Controller/CheckController.php',          ]);     }     /**      * @param GoogleAdsClient $googleAdsClient      * @param int $customerId      * @return void      * @throws ApiException      */     public static function runExample(GoogleAdsClient $googleAdsClient, int $customerId){         $googleAdsServiceClient = $googleAdsClient->getGoogleAdsServiceClient();         // Creates a query that retrieves all campaigns.         $query = 'SELECT campaign.id, campaign.name FROM campaign ORDER BY campaign.id';         // Issues a search stream request.         /** @var GoogleAdsServerStreamDecorator $stream */         $stream = $googleAdsServiceClient->searchStream($customerId, $query);         // Iterates over all rows in all messages and prints the requested field values for         // the campaign in each row.         foreach ($stream->iterateAllElements() as $googleAdsRow) {             /** @var GoogleAdsRow $googleAdsRow */             printf(                 "Campaign with ID %d and name '%s' was found.%s",                 $googleAdsRow->getCampaign()->getId(),                 $googleAdsRow->getCampaign()->getName(),                 PHP_EOL             );         }         return $stream;     } }