Fixed NPE.

git-svn-id: http://svn.igniterealtime.org/svn/repos/messenger/trunk@621 b35dd754-fafc-0310-a699-88a17e54d16e

src/java/org/jivesoftware/messenger/audit/spi/AuditorImpl.java

@@ -206,7 +206,9 @@ public class AuditorImpl implements Auditor {
             }
         }
         try {
-            xmlWriter.flush();
+            if (xmlWriter != null) {
+                xmlWriter.flush();
+            }
         }
         catch (IOException ioe) {