Elisp: get stack trace for functions with suppressed errors (filter functions, post command hooks, etc.)

toggle-debug-on-hidden-error.el

;;;; Power debugging
(defun my/reraise-error (func &rest args)
  "Call function FUNC with ARGS and re-raise any error which occurs.
Useful for debugging post-command hooks and filter functions, which
normally have their errors suppressed."
  (condition-case err
      (apply func args)
    ((debug error) (signal (car err) (cdr err)))))

(defun toggle-debug-on-hidden-errors (func)
  "Toggle hidden error debugging for function FUNC."
  (interactive "a")
  (cond
   ((advice-member-p #'my/reraise-error func)
    (advice-remove func #'my/reraise-error)
    (message "Debug on hidden errors disabled for %s" func))
   (t
    (advice-add func :around #'my/reraise-error)
    (message "Debug on hidden errors enabled for %s" func))))

See also https://github.com/minad/vertico#debugging-vertico. The Vertico post-command-hook does not have any subtle bugs but some completion tables may have them. ;)