When a user tries to access a project without enough rights, he should get a nice and proper message

In branch management current code, when you do not have rights to access a project, you get an "500 internal server error" popup (due to NPE in UserPrefsServiceImpl.getUserPrefs()
// Check if the user exists on the project
UserService us = getUserService();
if (!us.isUserMemberOfProject(projectId, userName))

).
You should get something more explicit.
See in StudioApp,
@GET
@Path("studio.html")
public Object getHome() {

Which could allow for detecting parameter, and checking for access rights.