swiftmailer bad/missing attachment fix patch

swiftmailer-bad-missing-attachment-fix.patch

diff --git a/src/Plugin/Mail/SwiftMailer.php b/src/Plugin/Mail/SwiftMailer.php
index e9830ac..4e0bcb9 100644
--- a/src/Plugin/Mail/SwiftMailer.php
+++ b/src/Plugin/Mail/SwiftMailer.php
@@ -479,7 +479,15 @@ class SwiftMailer implements MailInterface, ContainerFactoryPluginInterface {
           $content = file_get_contents($image->uri);
         }
         else {
-          $content = file_get_contents(\Drupal::service('file_system')->realpath($image->uri));
+          $image_path = \Drupal::service('file_system')->realpath($image->uri);
+          if (empty($image_path)) {
+            continue;
+          }
+          $content = file_get_contents($image_path);
+        }
+
+        if (empty($content)) {
+          continue;
         }
 
         $filename = $image->filename;

Against 8.x-2.x (1ad24cdf841fe309f689fd3c8cdce1014114c27b)