An I-search's pre-command-hook is returning error

This bug report will be sent to the XEmacs Development Team, not to your local site managers!! Please write in English, because the XEmacs maintainers do not have translators to read other languages for them. In XEmacs 21.4 (patch 4) "Artificial Intelligence" [Lucid] (sparc-sun-solaris2.7) of Mon Jul 30 2001 on cub configured using `configure --compiler=/opt/spro62/SUNWspro/bin/cc --with-gcc=no --prefix=/work/external/harry --with-sparcworks --with-workshop --with-tooltalk '--site-includes=/usr/local/include /usr/local/gnu/include' --infopath=/usr/local/info:/usr/local/gnu/info '--site-libraries=/usr/local/lib /usr/local/gnu/lib' --with-xpm --with-ncurses=no --with-sound=native --with-jpeg=yes --with-png=yes --with-menubars=lucid --with-scrollbars=lucid' Please describe exactly what actions triggered the bug and the precise symptoms of the bug: Start an isearch-forward, getting a prompt "I-search: " on the message line. Without entering something on the message line, go back to the buffer and click. A message appears: (error/warning) Error in `pre-command-hook' (setting hook to nil): (wrong-type-argument integer-or-marker-p nil) setting all the pre-command-hooks to nil. Apparently isearch-pre-pre-command-hook or isearch-pre-command-hook in .../lisp/isearch-mode.elc is not catching errors. Unfortunately, the error message did not state which hook was allowing errors to escape it. The following gross hackery in my init.el helped catch the culprit: ;; try to figure what pre-command hooks is causing errors (run-at-time 1 5 'eval '(message "pre-command-hook: %s" pre-command-hook)) The relevent selection of the message log around the event is: pre-command-hook: (paren-nuke-extent pending-delete-pre-hook) pre-command-hook: (isearch-pre-pre-command-hook isearch-pre-command-hook paren-nuke-extent pending-delete-pre-hook) pre-command-hook: (isearch-pre-pre-command-hook isearch-pre-command-hook paren-nuke-extent pending-delete-pre-hook) pre-command-hook: nil hf Recent keystrokes: button1up C-s . p m C-s C-s C-s C-s C-s button1 button1up button1 button1up button1 button1up button1 button1up button1 button1up button1 button1up button1 button1up button1 button1up button1 button1up button1 button1up misc-user misc-user misc-user misc-user button1 button1up C-s button1 button1up misc-user button1 button1up button1 button1up button1 button1up C-s button1 button1up misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user button1 button1up misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user misc-user Recent messages (most recent first): Loading tm-edit...done Loading tm-edit... Loading tm-ew-d...done Loading tm-ew-d... Parsing /home/harry/.mailrc... done Parsing /home/harry/.mailrc... Loading mail-abbrevs...done Loading mail-abbrevs... pre-command-hook: nil pre-command-hook: nil