Steps to reproduce:
1. break the configuration of the default ExampleDS.
2. start EAP with dashbuilder
3. try to log in - white screen appears and following message (there are also other error messages explaining what's going on) is in server log:

ERROR [org.jboss.dashboard.ui.controller.ControllerServlet] (http-localhost.localdomain/127.0.0.1:8230-2) Error painting response. User might have seen something ugly in the browser if he is still there.

Although the error message is funny and I must admit I was amused, I doubt that messages like that should be presented to our customers.