I\'m starting with GWT and smartgwt, and I realized that when your code works on jetty will no necessarily work on Jboss.
Is there a way that I can debug exceptions or
I assume you already have the launch configurations set up correctly (pointing the launch environment to JBoss instead of embedded Jetty). If you are in dev mode you should already be able to debug the javacode. If you want to debug the client side code in production use browser's dev tools.
Regarding error handling There are two ways which you can handle the GWT client side exceptions.
I think you are after server side logging (in fact that's what we need in production mode) GWT has a well defined error handling mechanisms for both client and server side. These answers/posts will help you yo set up error handlers in your GWT app properly.
7 Tips for Exception Handling in GWT
Setup a remoteLoggingServlet in GWT