I think it crashes in some post codegen update cycle on the main window, which of course is bogus. I'll see if I can reproduce it and get a stacktrace. In the normal designer one can't get this as the code generation config dialog is modal and the main window can't be closed.
(edit). Of course... vs.net doesn't give you a stack trace.. why would it!
(edit) the editor pane is killed while the code generation still runs. So it's not really useful to provide a proper clean up, it won't work. The close has to be prevented somehow. Will have to investigate how to do that (as the vs.net tab is simply closed, no matter what)