Problems with ispell/flyspell

[Stefan Monnier <monnier@iro.umontreal.ca>]

I recently started to get problems with flyspell that seem to be due to
ispell.el.  Basically, the main symptom is that flyspell doesn't do anything
(none of the incorrect spellings are highlighted).
Most likely the problem is caused by the second problem below (because the
error is signalled while running flyspell-post-command-hook and it thus
causes post-command-hook to be set to nil).

- when I start flyspell-mode, I tend to get an error of the form:

   "Error: no word lists can be found for the language fr_CH"

  this error is raised in ispell-init-process by
  (error "%s" (mapconcat 'identity ispell-filter "\n"))

- later on, while using flyspell, I get errors of the form
  "wrong-argument-type, string, nil" because
  in ispell-find-aspell-dictionaries, (assoc "en" ispell-dictionary-alist)
  has returned nil, which caused ispell-dictionary-alist to have an entry of
  the form (nil), so when ispell-current-dictionary is nil,
  (ispell-get-decoded-string 1) returns nil, so ispell-get-casechars returns
  nil, so flyspell-get-casechars returns nil, so flyspell-get-word
  does a (looking-at nil) which signals an error.

This is on a machine where I have both ispell and aspell installed
(as I just discovered), in case it matters.

~-0% ispell -v
@(#) International Ispell Version 3.1.20 10/10/95, patch 1
...
~-0% aspell -v
@(#) International Ispell Version 3.1.20 (but really Aspell 0.60.4)
~-0% 

All this is somewhat mostly reproducible, tho it doesn't seem to be
100% deterministic.


        Stefan