The fix yesterday allowing java.net.URL instances to be passed to TupleResultBuilder.namedResult(String, Object) introduced a bit of weirdness to the Repositories list screen. Whereas before, it displayed static text representing the repository URL, now it gives a link.
However, the link, as with all other links in Workbench tables, attempts to "Explore" the URL as a resource. Since the current repository on the Repositories page is "NONE", this results in a Server Error page.
The probable fix is to have the servlet pass the URL to the builder as its String representation instead.