How to show login errors in index.html

[hri101]

I have a question related to trapping and showing server error messages in index.html.

If for example we change method "authenticate" in class WebSecurityConfig as follows:

UsernamePasswordAuthenticationToken token = (UsernamePasswordAuthenticationToken) authentication; if("aaa".equals(token.getCredentials())) throw new AuthenticationException("'aaa' bad password") {};

When logging on using password 'aaa' the user is not logged on, index.html is presented but no error message is displayed.

Is this possible to extend the example to show such errors?