Re: failure in emacs notmuch-show: notmuch-show--register-cids: Wrong type argument: char-or-string-p, nil

[Jonas Bernoulli <jonas@bernoul.li>]

Daniel Kahn Gillmor <dkg@fifthhorseman.net> writes:

> My elisp is too weak to know how to debug this well.  suggestions
> welcome!

"M-x toggle-debug-on-error" and then trying to show the message should
give you a backtrace.  But before doing that also "M-x eval-buffer" in
"notmuch-show.el" to make it more meaningful.

>     notmuch-show--register-cids: Wrong type argument:
>     char-or-string-p, nil

With only that information my guess is that
  (plist-get part :content-type)
returns nil, which "downcase" understandably isn't happy with.

The "part" plist comes from "notmuch show ..." in
"notmuch-query-get-threads", so one problem seems to be that that
can return nil as the type (as opposed to e.g. "unknown/unknown")
while this elisp function (and maybe others) expect a string.

> 0 dkg@alice:~$ notmuch show --decrypt=false --format=raw id:$messageid  | email-print-mime-structure --use-gpg-agent
> └┬╴multipart/encrypted 27703 bytes
>  ├─╴application/pgp-encrypted 11 bytes
>  └─╴application/octet-stream inline [encrypted.asc] 23828 bytes
>   ↧ (decrypts to)
>   └┬╴multipart/mixed 26085 bytes
>    ├─╴text/plain 1028 bytes
>    └┬╴message/rfc822 attachment [attachment.eml] 24707 bytes
>     └─╴text/plain 24510 bytes

And another problem seems to be that notmuch cannot determine the type
of some part even though "email-print-mime-structure" can.  You should
be able to figure out which part by adding a debug statement such as:

  (message "> %S" part)

     Cheers,
     Jonas