Fix non dotted pair element issue

Every element of auto-mode-list are not dotted pair. For example
.gpg, .gz etc. assoc-default returns list for such buffer names and
funcall raises error because it is not function.

core/prelude-editor.el

@@ -183,6 +183,8 @@ The body of the advice is in BODY."
   "Set buffer major mode according to `auto-mode-alist'."
   (let* ((name (buffer-name buffer))
          (mode (assoc-default name auto-mode-alist 'string-match)))
+    (when (and mode (consp mode))
+      (setq mode (car mode)))
     (with-current-buffer buffer (if mode (funcall mode)))))
 
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