The method replaceAllShapeWithImage throw Internal error encountered

Question

I'm working on generation of Google Presentation (template with more than 50 slides) using PHP SDK, and recently when I use the method replaceAllShapeWithImage, it takes a long time to throw one of theses messages :

Error Message 1 :

{ "error": { "code": 500, "message": "Internal error encountered.", "errors": [ { "message": "Internal error encountered.", "domain": "global", "reason": "backendError" } ], "status": "INTERNAL" } }

Error Message 2:

{ "error": { "code": 503, "message": "The service is currently unavailable.", "errors": [ { "message": "The service is currently unavailable.", "domain": "global", "reason": "backendError" } ], "status": "UNAVAILABLE" } }

Here's some code to test:

function replaceAllShapeWithImageT(array &$requests,  $objectId,  $image_url, $replace_mothod ='CENTER_CROP')
{
        $requests[] = new Google_Service_Slides_Request(array(
              'replaceAllShapesWithImage' => array(
                'imageUrl' => $image_url,
                'imageReplaceMethod' => $replace_mothod,
                'containsText' => array(
                  'text' => $objectId,
                  'matchCase' => true
                )
            )
        ));
}


function testGenBatch($client)
{
    echo "\n STart";
    $slidesService = new Google_Service_Slides($client); 
    $presentationCopyId ='SLIDE_ID';
    $requests = [];
    replaceAllShapeWithImageT($requests, '{{destination_image}}', "https://picsum.photos/1400/800?image=1076");
    replaceAllShapeWithImageT($requests, '{{client_logo}}', "https://picsum.photos/400/200?image=1069");
    replaceAllShapeWithImageT($requests, '{{country_image}}', "https://picsum.photos/1400/800?image=1073");


    replaceAllShapeWithImageT($requests, '{{hotel_0_thumb}}', "https://picsum.photos/900/500");
    replaceAllShapeWithImageT($requests, '{{hotel_1_image_1}}', "https://picsum.photos/1400/800?image=1079");
    replaceAllShapeWithImageT($requests, '{{hotel_1_image_2}}', "https://picsum.photos/1400/800?image=1080");
    replaceAllShapeWithImageT($requests, '{{hotel_1_image_3}}', "https://picsum.photos/1400/800?image=1082");

    $batchUpdateRequest = new Google_Service_Slides_BatchUpdatePresentationRequest(array(
      'requests' => $requests
    ));
    try {
        echo "\n Launch BAtch Request\n";
        $response = $slidesService->presentations->batchUpdate($presentationCopyId, $batchUpdateRequest);
        // var_dump($response);
        echo "\n DOOOOOOOOOOOOOOOOOOOOOONE\n";
    } catch(\Exception $e) {
        echo "\nErrooor : ".$e->getMessage()."\n====================================================\n";
    }
}

Thank you