(funcall notmuch-show-mark-read-function (window-start) (window-end))
((debug error)
(unless notmuch-show--seen-has-errored
- (setq notmuch-show--seen-has-errored 't)
+ (setq notmuch-show--seen-has-errored t)
(setq header-line-format
(concat header-line-format
(propertize