code: @Override
  	protected void append(LoggingEvent event) {
  		final Throwable throwable;
  		if (event.getThrowableInformation() == null) {
  			throwable = null;
  		} else {
  			throwable = event.getThrowableInformation().getThrowable();
  		}
  		LoggingHandler.addErrorLogToCounter(getLayout().format(event), throwable);
  	}
docs: {@inheritDoc}