I wanted to mark certain filenames as images and added this to my config.el:
(add-to-list 'image-file-name-regexps "/preview/")
But when I run
org-toggle-inline-images now, I get the following error.
image-file-name-regexp: Wrong type argument: characterp, "/preview/"
Even though it says:
image-file-name-regexps is a variable defined in image-file.el.gz. Value ("/preview/") Documentation List of regexps matching image-file filenames.
And the variable is clearly a list.