[O] Bug: Remote column editing from agenda is broken [9.1.1 (9.1.1-6-gd40deb-elpa @ /Users/bnbeckwith/.emacs.d/elpa/org-20170925/)]

[Benjamin Beckwith]

Given a list of agenda files, I can bring up a global view of all
tasks. Then, if I enter into column mode and try to edit one of the
columns (say priority), it complains about the marker.

My config is the minimal one found on
http://orgmode.org/manual/Feedback.html. The agenda file I used is very
simple.

--8<---------------cut here---------------start------------->8---
* TODO One
* TODO Two
* TODO Three
--8<---------------cut here---------------end--------------->8---

I then add this to the agenda file list. And then use 'org-agenda'
followed by 't' to bring up a list of all todo items.  I enter into
column mode and place my cursor into the PRIORITY column. When I try to
press '1' to change the priority, I get the following stack trace.

The stack trace is:
--8<---------------cut here---------------start------------->8---
Debugger entered--Lisp error: (wrong-type-argument markerp nil)
  org-columns-remove-overlays()
  org-agenda-columns()
  org-columns-next-allowed-value(nil 1)
  (lambda nil (interactive) (org-columns-next-allowed-value nil 1))()
  funcall-interactively((lambda nil (interactive) 
(org-columns-next-allowed-value nil 1)))
  call-interactively((lambda nil (interactive) (org-columns-next-allowed-value 
nil 1)) nil nil)
  command-execute((lambda nil (interactive) (org-columns-next-allowed-value nil 
1)))
--8<---------------cut here---------------end--------------->8---

It seems that in `org-columns-remove-overlays` the
`org-columns-top-level-marker` is nil, so the `set-marker` call
fails. I'm not sure of the underlying mechanics of how the markers work,
but mabye a nil check here would suffice?

------------------------------------------------------------------------

Emacs  : GNU Emacs 25.3.1 (x86_64-apple-darwin16.7.0, NS appkit-1504.83 Version 
10.12.6 (Build 16G29))
 of 2017-09-15
Package: Org mode version 9.1.1 (9.1.1-6-gd40deb-elpa @ 
/Users/bnbeckwith/.emacs.d/elpa/org-20170925/)

current state:
==============
(setq
 org-tab-first-hook '(org-babel-hide-result-toggle-maybe
                      org-babel-header-arg-expand)
 org-speed-command-hook '(org-speed-command-activate
                          org-babel-speed-command-activate)
 org-occur-hook '(org-first-headline-recenter)
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-confirm-shell-link-function 'yes-or-no-p
 org-after-todo-state-change-hook '(org-clock-out-if-current)
 org-src-mode-hook '(org-src-babel-configure-edit-buffer
                     org-src-mode-configure-edit-buffer)
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-babel-pre-tangle-hook '(save-buffer)
 org-mode-hook '(#[0 "\300\301\302\303\304$\207"
                   [add-hook change-major-mode-hook org-show-block-all append
                    local]
                   5]
                 #[0 "\300\301\302\303\304$\207"
                   [add-hook change-major-mode-hook org-babel-show-result-all
                    append local]
                   5]
                 org-babel-result-hide-spec org-babel-hide-all-hashes)
 org-bibtex-headline-format-function #[257 "\300
\236A\207" [:title] 3 "\n\n(fn 
ENTRY)"]
 org-archive-hook '(org-attach-archive-delete-maybe)
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers
                  org-cycle-show-empty-lines
                  org-optimize-window-after-visibility-change)
 org-confirm-elisp-link-function 'yes-or-no-p
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 org-link-parameters '(("id" :follow org-id-open)
                       ("rmail" :follow org-rmail-open :store
                        org-rmail-store-link)
                       ("mhe" :follow org-mhe-open :store org-mhe-store-link)
                       ("irc" :follow org-irc-visit :store org-irc-store-link)
                       ("info" :follow org-info-open :export org-info-export
                        :store org-info-store-link)
                       ("gnus" :follow org-gnus-open :store
                        org-gnus-store-link)
                       ("docview" :follow org-docview-open :export
                        org-docview-export :store org-docview-store-link)
                       ("bibtex" :follow org-bibtex-open :store
                        org-bibtex-store-link)
                       ("bbdb" :follow org-bbdb-open :export org-bbdb-export
                        :complete org-bbdb-complete-link :store
                        org-bbdb-store-link)
                       ("w3m" :store org-w3m-store-link) ("file+sys")
                       ("file+emacs") ("doi" :follow org--open-doi-link)
                       ("elisp" :follow org--open-elisp-link)
                       ("file" :complete org-file-complete-link)
                       ("ftp" :follow
                        (lambda (path) (browse-url (concat "ftp:" path))))
                       ("help" :follow org--open-help-link)
                       ("http" :follow
                        (lambda (path) (browse-url (concat "http:" path))))
                       ("https" :follow
                        (lambda (path) (browse-url (concat "https:" path))))
                       ("mailto" :follow
                        (lambda (path) (browse-url (concat "mailto:"; path))))
                       ("news" :follow
                        (lambda (path) (browse-url (concat "news:"; path))))
                       ("shell" :follow org--open-shell-link))
 org-agenda-files '("~/test.org")
 org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
 )