Correct some more custom type specs

* lisp/winner.el (winner-boring-buffers-regexp):
* lisp/progmodes/js.el (js-jsx-indent-level):
* lisp/image-dired.el (image-dired-external-viewer):
* lisp/gnus/nnir.el (nnir-notmuch-filter-group-names-function):
Correct custom type specification.

* lisp/textmodes/bibtex.el (bibtex-string-file-path):
(bibtex-file-path): Correct custom type specification and document
source of initial value.

1 files changed, 10 insertions, 4 deletions

diff --git a/lisp/textmodes/bibtex.el b/lisp/textmodes/bibtex.el
index 7e99032084e..c29e9631801 100644
--- a/lisp/textmodes/bibtex.el
+++ b/lisp/textmodes/bibtex.el
@@ -933,9 +933,12 @@ to the directories specified in `bibtex-string-file-path'."
   :type '(repeat file))
 
 (defcustom bibtex-string-file-path (getenv "BIBINPUTS")
-  "Colon-separated list of paths to search for `bibtex-string-files'."
+  "Colon-separated list of paths to search for `bibtex-string-files'.
+Initialized from the BIBINPUTS environment variable."
   :group 'bibtex
-  :type 'string)
+  :version "27.1"
+  :type '(choice string
+                 (const :tag "Not Set" nil)))
 
 (defcustom bibtex-files nil
   "List of BibTeX files that are searched for entry keys.
@@ -949,9 +952,12 @@ See also `bibtex-search-entry-globally'."
                          directory file)))
 
 (defcustom bibtex-file-path (getenv "BIBINPUTS")
-  "Colon separated list of paths to search for `bibtex-files'."
+  "Colon separated list of paths to search for `bibtex-files'.
+Initialized from the BIBINPUTS environment variable."
   :group 'bibtex
-  :type 'string)
+  :version "27.1"
+  :type '(choice string
+                 (const :tag "Not Set" nil)))
 
 (defcustom bibtex-search-entry-globally nil
   "If non-nil, interactive calls of `bibtex-search-entry' search globally.