Fixed WSODs and warnings.

islandora.module

@@ -327,10 +327,14 @@ function islandora_form_alter(&$form, FormStateInterface $form_state, $form_id)
 
   if (in_array($form['#form_id'], $media_add_forms)) {
     $params = \Drupal::request()->query->all();
+    if (count($params) > 0 && array_key_exists('edit', $params)) {
       $media_of_nid = $params['edit']['field_media_of']['widget'][0]['target_id'];
       $node = \Drupal::entityTypeManager()->getStorage('node')->load($media_of_nid);
+      if ($node) {
         $form['name']['widget'][0]['value']['#default_value'] = $node->getTitle();
       }
+    }
+  }
 }
 
 /**
@@ -346,10 +350,14 @@ function islandora_field_widget_image_image_form_alter(&$element, $form_state, $
 function islandora_add_default_image_alt_text($element, $form_state, $form) {
   if ($element['alt']['#access']) {
     $params = \Drupal::request()->query->all();
+    if (count($params) > 0 && array_key_exists('edit', $params)) {
       $media_of_nid = $params['edit']['field_media_of']['widget'][0]['target_id'];
       $node = \Drupal::entityTypeManager()->getStorage('node')->load($media_of_nid);
+      if ($node) {
         $element['alt']['#default_value'] = $node->getTitle();
       }
+    }
+  }
   return $element;
 }