973848 - ISE in case no file specified.

Commit  81b58118809c58459544376d0ca9cdbfb175ecb2
introduces  ISE - Unhandled Exception thrown: class java.lang.NullPointerException in:
code/src/com/redhat/rhn/frontend/struts/StrutsDelegate.java
    public void addError(ActionErrors errors, String msgKey, Object...params) {
        ActionMessages msg = new ActionMessages();
        msg.add(ActionMessages.GLOBAL_MESSAGE, new ActionMessage(msgKey,
                params));
        errors.add(msg);
    }