suppress error message if WikiRbacPatch was not fully configured

[mark@…]

If you apply the patch and start your webserver for the first time, without having configured Trac by modifying trac.ini, this error is displayed:

 Trac detected an internal error:

'Authorizer' object has no attribute 'module_name'

Of course, the instructions say that three lines have to be added to trac.ini.

But it would be nice if the error was just logged and not displayed, WikiRbac was just inactive and every page displayed as if there was no such patch applied.

[puffy]

You misconfiguring Trac is not my problem.