gistfile1.txt

Debugger entered--Lisp error: (wrong-type-argument stringp nil)
  org-element--headline-deferred((headline ...))
  apply(org-element--headline-deferred (headline ...) nil)
  org-element--property(:deferred (headline ...) nil force-undefer)
  org-element--property(:ID (headline ...) nil nil)
  #<subr org-element--cache-verify-element>((headline ...))
  apply(#<subr org-element--cache-verify-element> (headline ...))
  org-element--cache-verify-element((headline ...))
  org-element-at-point(nil cached)
  org-before-first-heading-p()
  org-back-to-heading-or-point-min(t)
  org-end-of-subtree(t t)
  org-refresh-stats-properties()
  org-agenda-prepare-buffers(...)
  org-map-entries(org-alert--dispatch "SCHEDULED>=\"<today>\"+SCHEDULED<\"<tomorrow>\"|DEADLI..." agenda (org-agenda-skip-entry-if 'todo org-done-keywords-for-agenda))
  org-alert-check()
  apply(org-alert-check nil)
  timer-event-handler([t 26391 53503 551457 300 org-alert-check nil nil 0 nil])