Question about null environmental object

[Toby Hobson <to...@googlemail.com>]

I have a two components: TabSet and Tab. TabSet retrieves the user who is
currently logged in (if the user has logged in) from acegi, does some
processing and makes it available to nested components via the environmental
service:

void beginRender() {
 if (loggedUser == null)
 return;
 // process user
 environment.push(User.class, loggedUser);
}

void afterRender() {
 if (environment.peek(User.class) != null)
  environment.pop(User.class);
}

The Tab uses this value to work out whether it should render itself:

@Environmental
private User loggedUser;

boolean setupRender() {
  if (loggedUser != null)
  // check if the user should see this tab
}

This all works nicely assuming the user has logged in, but if there is no
User object on the environment stack it all falls over. The line if
(loggedUser != null) causes T5 to throw an exception because no User object
is on the stack. So my question is what is the best way to handle a
situation in which an Environmental object could be null? I was thinking I
may have to inject the environment service into the Tab component and peek
at the stack like I do in TabSet.afterRender() but this seems a little
messy.

Thanks

Toby