Syntax for setting variables org-download-image-dir wrong-type-argument stringp nil

[rickalex21]

Hello, thank you for your contribution to this project.

I am getting this error. It looks like I can not set the variable dynamically. I am
not sure if something has changed in Emacs recently or if I am doing something
wrong? I have seen several users use the concat function like this.

Debugger entered--Lisp error: (wrong-type-argument stringp nil)
  file-name-base(nil)
  (concat "./images/" (file-name-base (buffer-file-name)) "/")

As a work around I put it in a let:

(evil-define-key 'normal org-mode-map (kbd "C-v") (lambda ()(interactive) ; mac requires brew pngpaste - add ctrl use cmd+ctrl+shift+4
                                                      (let* ((name (read-string "Enter file name without extension:"))
                                                              (org-download-image-dir (concat  "./images/" (file-name-base (buffer-file-name)) "/" ))
                                                              (org-download-screenshot-basename (concat name (format-time-string "-%Y-%m-%dT%H%M%S") ".png")))
                                                      (org-download-clipboard (concat name ".png")))))

Here is my full configuration:

(use-package org-download
  :straight t
  :after org
  :hook ((org-mode dired-mode) . org-download-enable)
  :init
  (setq-default org-download-screenshot-method
                (if (featurep :system 'linux) "grim -g \"$(slurp)\" %s"
                     "screencapture -i %s")) ; assume 'macos
  (setq org-download-image-dir (concat  "./images/" (file-name-base (buffer-file-name)) "/" )
        org-download-heading-lvl nil ; Removes the dir it creates based on the heading
        org-download-image-attr-list '("#+caption:" "#+attr_latex: :width 1500pt" "#+attr_org: :width 500") ; was 450px
        org-download-timestamp  "" ; do not add timestamp at the start of the name
        org-download-annotate-function (lambda (_link) "")) ; Remove #+DOWNLOAD
  :config
  (evil-define-key 'normal org-mode-map (kbd "C-v") (lambda ()(interactive) ; mac requires brew pngpaste - add ctrl use cmd+ctrl+shift+4
                                                      (let* ((name (read-string "Enter file name without extension:"))
                                                              (org-download-image-dir (concat  "./images/" (file-name-base (buffer-file-name)) "/" ))
                                                              (org-download-screenshot-basename (concat name (format-time-string "-%Y-%m-%dT%H%M%S") ".png")))
                                                      (org-download-clipboard (concat name ".png"))))))

Thanks