Calendar: Fix failing attachment upload in Calendar::editEvent()

Author: @TheTomcat14

main/inc/lib/agenda.lib.php

@@ -1201,10 +1201,14 @@ class Agenda
                 if (isset($attachmentArray) && !empty($attachmentArray)) {
                     $counter = 0;
                     foreach ($attachmentArray as $attachmentItem) {
-                        if (empty($attachmentItems['id'])) {
+                        if (empty($attachmentItem['id'])) {
-                            continue;
+                            $this->addAttachment(
-                        }
+                                $id,
-
+                                $attachmentItem,
+                                $attachmentCommentList[$counter],
+                                $this->course
+                            );
+                        } else {
                             $this->updateAttachment(
                                 $attachmentItem['id'],
                                 $id,
@@ -1212,6 +1216,7 @@ class Agenda
                                 $attachmentCommentList[$counter],
                                 $this->course
                             );
+                        }
                         $counter++;
                     }
                 }