- ;; that's the function that gets advised.
- (advice-add browse-url-browser-function :before-while
- (lambda (url &rest _args)
- "Handle gemini, gopher, and finger schemes using Elpher."
- (let ((scheme (downcase (car (split-string url ":" t)))))
- (if (member scheme '("gemini" "gopher" "finger"))
- ;; `elpher-go' always returns nil, which will stop the
- ;; advice chain here in a before-while
- (elpher-go url)
- ;; chain must continue, then return t.
- t)))))
+ ;; that's the function that gets advised. If the value is an alist,
+ ;; however, we don't know what to do. Better not interfere?
+ (when (and (symbolp browse-url-browser-function)
+ (fboundp browse-url-browser-function))
+ (advice-add browse-url-browser-function :before-while
+ (lambda (url &rest _args)
+ "Handle gemini, gopher, and finger schemes using Elpher."
+ (let ((scheme (downcase (car (split-string url ":" t)))))
+ (if (member scheme '("gemini" "gopher" "finger"))
+ ;; `elpher-go' always returns nil, which will stop the
+ ;; advice chain here in a before-while
+ (elpher-go url)
+ ;; chain must continue, then return t.
+ t))))))