Add error handling for startup failures

scripts/guix-data-service.in

@@ -200,6 +200,13 @@
       (start-substitute-query-threads)
 
       (call-with-new-thread
+       (lambda ()
+         (with-exception-handler
+             (lambda (exn)
+               (simple-format
+                (current-error-port)
+                "startup failed: ~A\n" exn)
+               (exit 1))
            (lambda ()
              (run-sqitch)
 
@@ -216,7 +223,7 @@
                "poll-startup"
                all-git-repositories))
 
-         (atomic-box-set! startup-completed #t)))
+             (atomic-box-set! startup-completed #t)))))
 
       ;; Provide some visual space between the startup output and the
       ;; server starting