added islandora.libraries.yml

css/islandora.theme.css

@@ -0,0 +1,3 @@
+.container .islandora-media-items {
+  margin: 0;
+}

islandora.libraries.yml

@@ -0,0 +1,5 @@
+drupal.islandora.theme_css:
+  version: VERSION
+  css:
+    theme:
+      css/islandora.theme.css: {}

islandora.module

@@ -357,8 +357,8 @@ function islandora_form_alter(&$form, FormStateInterface $form_state, $form_id)
           '#theme' => 'item_list',
           '#type' => 'ul',
           '#items' => $media_list,
-          '#attributes' => ['class' => 'mylist'],
-          '#wrapper_attributes' => ['class' => 'container'],
+          '#attributes' => ['class' => ['islandora-media-items']],
+          '#wrapper_attributes' => ['class' => ['container']],
           '#attached' => [
             'library' => [
               'islandora/drupal.islandora.theme_css',
@@ -454,7 +454,7 @@ function islandora_object_delete_form_submit($form, &$form_state) {
 
     if ($delete_files) {
       $file_storage->delete($delete_files);
-      foreach ($delete_files as $file) {
+      foreach ($delete_files as $id => $file) {
         $logger->notice('The file %label has been deleted.', [
           '%label' => $file->label(),
         ]);
@@ -489,15 +489,18 @@ function islandora_object_delete_form_submit($form, &$form_state) {
         '#type' => 'html_tag',
         '#tag' => 'div',
         '#value' => t("The repository item @node and @media", [
-          '@node' => $node->getTitle(),
-          '@media' => \Drupal::translation()->formatPlural(
+          '#value' => t("The repository item @node and @media", [
+            '@node' => $node->getTitle(),
+            '@media' => \Drupal::translation()->formatPlural(
             substr_count($media_list, ",") + 1, 'the media with the id @media has been deleted.',
             'the medias with the id @media have been deleted.',
             ['@media' => mb_substr($media_list, 0, strlen($media_list) - 2)]),
+          ]),
         ]),
       ],
     ];
 
+
     $message = \Drupal::service('renderer')->renderPlain($build);
     $messenger->deleteByType('status');
     $messenger->addStatus($message);