ZP-501 #comment check if key exists in array before accessing it

git-svn-id: https://z-push.org/svn/z-push/trunk@1870 b7dd7b3b-3a3c-0410-9da9-bee62a6cc5b5

src/backend/zarafa/mapi/class.recurrence.php

@@ -844,7 +844,7 @@
 
                     $data = mapi_message_getprops($exception, array($this->proptags["basedate"]));
 
-                    if($this->isSameDay($this->fromGMT($this->tz,$data[$this->proptags["basedate"]]), $base_date)) {
+                    if(isset($data[$this->proptags["basedate"]]) && $this->isSameDay($this->fromGMT($this->tz,$data[$this->proptags["basedate"]]), $base_date)) {
                         return $tempattach;
                     }
                 }