move the captcha checking code inside the handler

that deals with expected networking errors

closes PR 13205

collects/help/bug-report.rkt

@@ -206,6 +206,7 @@
                      [current-alist-separator-mode 'amp])
         (thread
          (λ ()
+           (with-handlers ([exn:fail? (λ (x) (channel-put exn-chan x))])
              ;; Note that this UI is not great: every submission asks for a
              ;; captcha and nothing is kept.  This is fine since this is only in
              ;; case it needs to be used in the future -- if/when that happens,
@@ -232,7 +233,7 @@
                                ,@q)
                              q)])
                  (string->bytes/utf-8 (alist->form-urlencoded q))))
-           (with-handlers ([exn:fail? (λ (x) (channel-put exn-chan x))])
+
              (call/input-url
               bug-report-url
               (lambda (x) (post-impure-port x post-data))