Fix 'apropos-library' for 'define-symbol-props'

* lisp/apropos.el (apropos-library): Sanitize data to avoid
signaling errors when 'define-symbol-props' is seen.  (Bug#72616)

1 files changed, 4 insertions, 1 deletions

diff --git a/lisp/apropos.el b/lisp/apropos.el
index 6c6cd0b593d..0655fecd0e8 100644
--- a/lisp/apropos.el
+++ b/lisp/apropos.el
@@ -734,7 +734,10 @@ the output includes key-bindings of commands."
         ;; FIXME: Print information about each individual method: both
         ;; its docstring and specializers (bug#21422).
         ('cl-defmethod (push (cadr x) provides))
-        (_ (push (or (cdr-safe x) x) symbols))))
+        ;; FIXME: Add extension point (bug#72616).
+        (_ (let ((sym (or (cdr-safe x) x)))
+             (and sym (symbolp sym)
+                  (push sym symbols))))))
     (let ((apropos-pattern "") ;Dummy binding for apropos-symbols-internal.
           (text
            (concat