>>> "LI" == Lars Ingebrigtsen <larsi@gnus.org> writes:

   > Uwe Brauer <oub@mat.ucm.es> writes:
   >> Debugger entered--Lisp error: (search-failed "--text follows this line--")
   >> search-forward("--text follows this line--")
   >> hashcash-insert-payment-async-2(#<buffer *unsent wide reply to
   >> Noah Graff*> #<process hashcash<6>>
   >> "1:20:190823:oub@mat.ucm.es::r8emlzGlkUiiQhTF:0002J...")

   > [...]

   >> read-event(nil t 2)
   >> sit-for(2)
   >> sc-mail-error-in-mail-field()
   >> eval((sc-mail-error-in-mail-field))

   > [...]

   >> sc-cite-original()
   >> run-hooks(mail-citation-hook)

   > It looks like this is a bug in the third-party SuperCite package?

Oops right the code in question is 
(add-hook 'mail-citation-hook 'sc-cite-original)

Removing the function from the hook resolved the problem for this
message.

The strange thing it only happens to this particular message, your
message does not cause any problems with supercite.

But then supercite is quite old and (1993) maintainer is 
;; Maintainer: emacs-devel@gnu.org

So what do you say. 

How can this problem be debugged?