(describe-current-coding-system):

Check if each coding category is bound to a valid coding system.

diff --git a/lisp/international/mule-diag.el b/lisp/international/mule-diag.el
index 188a681370ca95d0833bd13e15a2d62c4c0ddeb8..a32d892b03c6e057a6fe5c0f5f64b6e7eb8fa948 100644 (file)
--- a/lisp/international/mule-diag.el
+++ b/lisp/international/mule-diag.el
@@ -336,7 +336,7 @@ at the place of `..':
        (while l
          (setq coding (symbol-value (car l)))
          ;; Do not list up the same coding system twice.
-         (when (not (memq coding coding-list))
+         (when (and coding (not (memq coding coding-list)))
            (setq coding-list (cons coding coding-list))
            (princ (format "  %d. %s " i coding))
            (setq aliases (coding-system-get coding 'alias-coding-systems))