🚀 go-pugleaf

If you kill VM's summary buffer, it gives an error
(wrong-type-argument stringp nil) on further use of the folder.
Killing the buffer is perhaps unfriendly, but since one can run
without it altogether, I think that giving an error is rather
unfriendly too, and a bug.  The version: vm-version's value is "5.32
(beta)", and emacs-version says

GNU Emacs 18.55.1 of Mon Aug 28 1989 on cfa244.harvard.edu (berkeley-unix)

It was compiled with version 2.04 of Jamie Zawinsky's optimizing
byte-compiler. To reproduce the error:

emacs -q
M-x load-file <ret> ~/emacs/lisp/vm.elc <ret>
M-x vm-visit-folder <ret> /tmp/foo <ret>
h
C-x o
C-x k <ret>
C-x o
s /tmp/bar <ret>

And that gives the error. Usually I don't make use of the summary, so
I didn't notice this until recently. The same error appears using
emacs 18.57.1. All this is on a SS-1 running SunOS 4.1.1, if that
matters. The 18.55 version is without window support (running in an
xterm), and the 18.57.1 with window support (creating its own window).

Below is the debugger output if I setq debug-on-error
to t (I deleted the byte-code stuff that looked binary; I hope what
remains will make it through the news). 

Signalling: (wrong-type-argument stringp nil)
  byte-code("" [m 2 0 6 7 nil summary m-list 1 buffer-name marker-buffer vm-sprintf vm-summary-format t buffer-read-only inhibit-quit 32 "  " "->" delete-region 3] 5)
  vm-update-message-summary([[#<marker at 1 in INBOX> #<marker at 493 in INBOX> #<marker at 666 in INBOX> #<marker at 8320 in INBOX> nil nil <<>> nil <--] ["1" nil #<marker in no buffer> #<marker in no buffer>] [nil nil nil t nil nil nil nil nil] [nil "Tue" "28" "April" "92" "13:11:00" "EDT" "Kenneth S. K. Lum" "ksl " nil "146" "EXITE2 Center of Gravity" "^From:" nil nil "4"] nil])
  byte-code("" [vm-do-needed-renumbering vm-do-needed-summary-rebuild vm-message-pointer 1 0 vm-ml-message-number 2 "new" vm-ml-attributes-string "unread" "read" 7 " edited" 3 " filed" 5 " written" 4 " replied" 6 " forwarded" " deleted" " MARKED" vm-summary-buffer vm-real-buffers vm-copy-local-variables vm-ml-highest-message-number vm-buffer-modified-p vm-message-list vm-messages-needing-display-update vm-update-message-summary vm-deferred-message message nil vm-force-mode-line-update] 8)
  vm-update-summary-and-mode-line()
  byte-code("" [showing vm-system-state vm-message-pointer vmp vm-sbe-buffer major-mode vm-virtual-mode vm-message-list marker-buffer 0 ((byte-code "" [vm-sbe-buffer buffer-name] 2)) widen narrow-to-region vm-text-end-of vm-honor-page-delimiters looking-at page-delimiter forward-page 1 vm-narrow-to-page 2 vm-set-new-flag nil vm-set-unread-flag vm-update-summary-and-mode-line] 4)
  vm-show-current-message()
  byte-code("" [previewing vm-system-state vm-sbe-buffer major-mode vm-virtual-mode vm-message-list marker-buffer vm-message-pointer 0 ((byte-code "" [vm-sbe-buffer buffer-name] 2)) get-buffer-window one-window-p t vm-display-current-message-buffer vmp ((byte-code "" [vm-sbe-buffer buffer-name] 2)) widen narrow-to-region vm-vheaders-of vm-preview-lines vm-text-end-of vm-text-of forward-line natnump vm-honor-page-delimiters vm-narrow-to-page w set-window-start vm-highlight-headers vm-preview-read-messages 2


 1 vm-show-current-message vm-update-summary-and-mode-line] 7)
  vm-preview-current-message()
  byte-code("" [vm-mail-buffer buffer-name vm-sanity-check-modification-flag bufferp vm-summary-buffer nil signal-errors vm-error-if-folder-empty count 1 vm-message-pointer 0 forward backward vm-abs direction error oldmp vm-message-list (byte-code "" [count 0 vm-move-message-pointer direction] 3) ((beginning-of-folder (byte-code "" [beginning-of-folder error] 1)) (end-of-folder (byte-code "" [end-of-folder error] 1))) (byte-code "" [vm-move-message-pointer direction oldmp vm-message-pointer vm-should-skip-


message t retry vm-message-list] 3) ((beginning-of-folder (byte-code "" [oldmp vm-message-pointer retry nil (byte-code "" [vm-message-pointer vm-move-message-pointer direction vm-should-skip-message] 2) ((beginning-of-folder (byte-code "" [beginning-of-folder error oldmp] 1))) beginning-of-folder error] 3)) (end-of-folder (byte-code "" [oldmp vm-message-pointer retry nil (byte-code "" [vm-message-pointer vm-move-message-pointer direction vm-should-skip-message] 2) ((end-of-folder (byte-code "" [end-of-fold


er error oldmp] 1))) end-of-folder error] 3))) vm-record-and-change-message-pointer t vm-need-summary-pointer-update vm-preview-current-message signal] 5)
  vm-next-message(-1 1 1)
  byte-code("" [count 1 vm-mail-buffer buffer-name vm-next-message retry signal-errors] 4)
  vm-previous-message(1 1 1)
* call-interactively(vm-previous-message)