Check for doc-spec-function early, in interactive invocation

* lisp/info-look.el (info-lookup-interactive-arguments):
Move here.
(info-lookup): From here.  (Bug#71314)

(cherry picked from commit d7be9fdbc009ecf314e1ae9166429188b6ddb121)

diff --git a/lisp/info-look.el b/lisp/info-look.el
index cd59fdf17d73a9e8e139ed26fda3d431a316c5c9..2baf133c7d3a10ebde80f448003de3b0f28bd671 100644 (file)
--- a/lisp/info-look.el
+++ b/lisp/info-look.el
@@ -327,8 +327,11 @@ string of `info-lookup-alist'.
 If optional argument QUERY is non-nil, query for the help mode."
   (let* ((mode (cond (query
                      (info-lookup-change-mode topic))
-                    ((info-lookup->mode-value topic (info-lookup-select-mode))
-                     info-lookup-mode)
+                    ((when-let
+                          ((info (info-lookup->mode-value
+                                  topic (info-lookup-select-mode))))
+                        (info-lookup--expand-info info))
+                      info-lookup-mode)
                     ((info-lookup-change-mode topic))))
         (completions (info-lookup->completions topic mode))
         (default (info-lookup-guess-default topic mode))
@@ -404,9 +407,6 @@ If SAME-WINDOW, reuse the current window.  If nil, pop to a
 different window."
   (or mode (setq mode (info-lookup-select-mode)))
   (setq mode (info-lookup--item-to-mode item mode))
-  (if-let ((info (info-lookup->mode-value topic mode)))
-      (info-lookup--expand-info info)
-    (error "No %s help available for `%s'" topic mode))
   (let* ((completions (info-lookup->completions topic mode))
          (ignore-case (info-lookup->ignore-case topic mode))
          (entry (or (assoc (if ignore-case (downcase item) item) completions)