Simplify exception handling in the web server

knots/web-server.scm

@@ -305,21 +305,7 @@ on the procedure being called at any particular time."
                                 (lambda ()
                                   (with-exception-handler
                                       (lambda (exn)
-                                        (let* ((stack (make-stack #t))
-                                               (error-string
-                                                (call-with-output-string
-                                                  (lambda (port)
-                                                    (print-exception
-                                                     port
-                                                     (stack-ref stack 2)
-                                                     '%exception
-                                                     (list exn))
-                                                    (display-backtrace
-                                                     stack
-                                                     port
-                                                     2)))))
-                                          (display error-string
-                                                   (current-error-port)))
+                                        (print-backtrace-and-exception/knots exn)
                                         (raise-exception exn))
                                     (lambda ()
                                       (body body-port)))