Subject: Bogus 'Error while printing exception' message when raising srfi-35 exception

From: Maxim Cournoyer <[email-masked]>
Date: Fri, 13 Jan 2023 20:30:44 -0500

Hello Guile,

When raising a srfi-35 defined exception type like in the following, a
generic (and unhelpful) "Error while printing exception" message is
shown, with not even the exception type mentioned:

--8<---------------cut here---------------start------------->8---
(use-modules (srfi srfi-35))

(define-condition-type &platform-not-found-error &error
  platform-not-found-error?)

(raise-exception &platform-not-found-error)
--8<---------------cut here---------------end--------------->8---

Produces:

--8<---------------cut here---------------start------------->8---
Backtrace:
In ice-9/boot-9.scm:
  1752:10  5 (with-exception-handler _ _ #:unwind? _ # _)
In unknown file:
           4 (apply-smob/0 #<thunk 7f236157a2e0>)
In ice-9/boot-9.scm:
    724:2  3 (call-with-prompt _ _ #<procedure default-prompt-handle…>)
In ice-9/eval.scm:
    619:8  2 (_ #(#(#<directory (guile-user) 7f2361580c80>)))
In ice-9/boot-9.scm:
   2836:4  1 (save-module-excursion _)
  4388:12  0 (_)

ice-9/boot-9.scm:4388:12: Error while printing exception.
--8<---------------cut here---------------end--------------->8---

This is probably not by design, right?

-- 
Thanks,
Maxim