define-generic-mode: unexpected handling of comment-end

[Kai Grossjohann]

It seems that it doesn't work to specify ("# " . "") for comments:

Debugger entered--Lisp error: (args-out-of-range "" 0)
  generic-mode-set-comments((("# " . "")))
  generic-mode-internal(baselib-config-mode (("# " . "")) ("include") nil nil)
  baselib-config-mode()
  set-auto-mode-0(baselib-config-mode nil)
  set-auto-mode()
  normal-mode(t)
  after-find-file(nil nil t t nil)
  revert-buffer(t)
  call-interactively(revert-buffer)

Specifying ("# " . nil) instead works as I intended ("# " . "") to work.

Shouldn't the documentation say that comment-end is handled specially?

Here's the code:

(define-generic-mode
  'baselib-config-mode                  ;name
  '(("# " . nil))                       ;comment-list
  '("include")                          ;keyword-list
  nil                                   ;font-lock-list
  '("\\.cfg\\'")                        ;auto-mode-list
  nil                                   ;function-list
  "Mode for editing baselib config files.")

Kai