cs & io: name for default error value conversion handler

racket/src/io/error/main.rkt

@@ -53,6 +53,7 @@
 ;; replacing the non-working primitive placeholder
 (define (install-error-value->string-handler!)
   (error-value->string-handler
+   (let ([default-error-value->string-handler
            (lambda (v len)
              (unless (exact-nonnegative-integer? len)
                (raise-argument-error 'default-error-value->string-handler
@@ -60,7 +61,8 @@
                                      len))
              (define o (open-output-string))
              (do-global-print 'default-error-value->string-handler v o 0 len)
-    (get-output-string o))))
+             (get-output-string o))])
+     default-error-value->string-handler)))
 
 (void (install-error-value->string-handler!))