prevent log error at shutdown

core/java/src/net/i2p/util/LogWriter.java

@@ -81,7 +81,7 @@ class LogWriter implements Runnable {
                     if (_currentOut != null)
                         _currentOut.flush();
                 } catch (IOException ioe) {
-                    if (++_diskFullMessageCount < MAX_DISKFULL_MESSAGES)
+                    if (_write && ++_diskFullMessageCount < MAX_DISKFULL_MESSAGES)
                         System.err.println("Error writing the router log - disk full? " + ioe);
                 }
             }