Issue #3479540:

• Handle the exception when offline images are sent to the Sidekick api

Closes #3479540

sidekick.module

@@ -15,6 +15,7 @@ use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Language\LanguageInterface;
 use Drupal\file\Entity\File;
 use Drupal\Core\Url;
+use GuzzleHttp\Exception\ClientException;
 use GuzzleHttp\RequestOptions;
 use Drupal\sidekick\ImageWidget;
 
@@ -859,20 +860,35 @@ function sidekick_image_ajax_callback(
         [
           "identifier" => "url",
           "value" => $image_url ?? '',
-          // todo handle api response errors as validation.
         ],
       ],
     ]);
     $request_options[RequestOptions::HEADERS]['Content-Type'] = 'application/json';
+    $request_options[RequestOptions::HEADERS]['Accept'] = 'application/json';
     $request_options[RequestOptions::HEADERS]['Authorization'] = 'Bearer ' . $sidekick_api_key;
-    $response = $client->request('POST', $api_url, $request_options);
-    $data = Json::decode((string) $response->getBody());
-    $data_from_sidekick = $data['data']['message']['message'] ?? '';
-    $response = new AjaxResponse();
-    $response->addCommand(
-      new InvokeCommand($element, 'val', [$data_from_sidekick])
-    );
-    return $response;
+
+    try {
+      $response = $client->request('POST', $api_url, $request_options);
+      $data = Json::decode((string) $response->getBody());
+      $data_from_sidekick = $data['data']['message']['message'] ?? '';
+      $response = new AjaxResponse();
+      $response->addCommand(
+        new InvokeCommand($element, 'val', [$data_from_sidekick])
+      );
+      return $response;
+    }
+    catch (ClientException $e) {
+      $response = new AjaxResponse();
+      return $response->addCommand(
+        new MessageCommand(
+          json_decode($e->getResponse()
+            ->getBody()
+            ->getContents())->message,
+          '.sidekick-message',
+          ['type' => 'error']
+        )
+      );
+    }
   }
 
   return [];