Fixed Drupal calls.

src/Form/SnippetDelete.php

@@ -6,12 +6,51 @@ use Drupal\Core\Form\ConfigFormBase;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Messenger;
 use Drupal\Core\Url;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Messenger\MessengerInterface;
+
 
 /**
  * Delete a Custom Text Snippet.
  */
 class SnippetDelete extends ConfigFormBase {
 
+  /**
+   * The config factory service.
+   *
+   * @var \Drupal\Core\Config\ConfigFactoryInterface
+   */
+  protected $configFactory;
+
+  /**
+   * The messenger service.
+   *
+   * @var \Drupal\Core\Messenger\MessengerInterface
+   */
+  protected $messenger;
+
+  /**
+   * Class constructor.
+   *
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
+   *   The config factory service.
+   */
+  public function __construct(ConfigFactoryInterface $config_factory, MessengerInterface $messenger) {
+    $this->configFactory = $config_factory;
+    $this->messenger = $messenger;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('config.factory'),
+      $container->get('messenger')
+    );
+  }
+
   /**
    * Returns a unique string identifying the form.
    *
@@ -77,7 +116,7 @@ class SnippetDelete extends ConfigFormBase {
       ]),
       '#description' => $this->t('Before deleting this snippet, it is recommended that you search your site codebase to ensure the machine name is not in use anywhere.'),
     ];
-    $content = \Drupal::config('content_snippets.content')->get($snip_id);
+    $content = $this->configFactory->get('content_snippets.content')->get($snip_id);
 
     $form['content'] = [
       '#prefix' => '<br /><h3>Current Content:</h3>',
@@ -105,7 +144,7 @@ class SnippetDelete extends ConfigFormBase {
     $items->clear($snip_id);
     $items->save();
     $form_state->setRedirect('content_snippets.config.snippets_config');
-    \Drupal::messenger()->addMessage("$snip_id deleted.");
+    $this->messenger->addMessage("$snip_id deleted.");
     parent::submitForm($form, $form_state);
   }