Relating to issue #1668, the proposed fix works when there is only one
service provider to logout of.

Now that multiple service provider logout is starting to work again on
2.0, we cannot read the remote_ProviderID from the logout object because
it is only filled by lasso when actually building the response.

Instead, we ignore any error that could occur when building the
response, log a warning and show the portal instead. Still better than
an internal server error.