Throw exception if document or file can't be loaded.

src/Plugin/AiCKEditor/SummarizeDocument.php

@@ -196,15 +196,13 @@ final class SummarizeDocument extends AiCKEditorPluginBase {
 
     $document = $this->entityTypeManager->getStorage('media')->load($values['plugin_config']['document']);
     if (!$document instanceof MediaInterface) {
-      $this->logger->error('Could not load the selected document.');
-      return $form['plugin_config']['response_text']['#value'] = 'Could not load the selected document.';
+      throw new \Exception('Could not load the selected document.');
     }
 
     $file_id = $document->getSource()->getSourceFieldValue($document);
     $file = $this->entityTypeManager->getStorage('file')->load($file_id);
     if (!$file instanceof FileInterface) {
-      $this->logger->error('Could not load the file from the selected document.');
-      return $form['plugin_config']['response_text']['#value'] = 'Could not load the file from the selected document.';
+      throw new \Exception('Could not load the file from the selected document.');
     }
 
     $parser = new Parser();