bug#38248: help-follow-symbol silent when no symbol was found

[Juanma Barranquero <lekktu@gmail.com>]

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Eli, are you OK with this (slightly) incompatible change?

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From 088bd2ab28ef17a0cba02ea47aca6a02da1ce939 Mon Sep 17 00:00:00 2001
From: Juanma Barranquero <lekktu@gmail.com>
Date: Fri, 22 Nov 2019 19:47:05 +0100
Subject: [PATCH] help-follow-symbol now tells that no symbol was found

* lisp/help-mode.el (help-follow-symbol): Signal user-error if
there's no symbol at point.

* etc/NEWS: Document it.
---
 etc/NEWS          | 4 ++++
 lisp/help-mode.el | 9 +++++----
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index b92fdeb675..013336835d 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -2588,6 +2588,10 @@ pointer is over.  To change this behaviour, you can customize the user
 option 'mouse-wheel-follow-mouse'.  Note that this will also affect
 scrolling.
 
+---
+** help-follow-symbol now signals user-error if point (or the position
+pointed to by the argument POS) is not in a symbol.
+
 \f
 * Lisp Changes in Emacs 27.1
 
diff --git a/lisp/help-mode.el b/lisp/help-mode.el
index 054a1ef8c2..e70570c3ee 100644
--- a/lisp/help-mode.el
+++ b/lisp/help-mode.el
@@ -749,10 +749,11 @@ help-follow-symbol
 	    (buffer-substring (point)
 			      (progn (skip-syntax-forward "w_")
 				     (point)))))))
-    (when (or (boundp sym)
-	      (get sym 'variable-documentation)
-	      (fboundp sym) (facep sym))
-      (help-do-xref pos #'describe-symbol (list sym)))))
+    (if (or (boundp sym)
+	    (get sym 'variable-documentation)
+	    (fboundp sym) (facep sym))
+        (help-do-xref pos #'describe-symbol (list sym))
+      (user-error "No symbol here"))))
 
 (defun help-mode-revert-buffer (_ignore-auto noconfirm)
   (when (or noconfirm (yes-or-no-p "Revert help buffer? "))
-- 
2.23.0.windows.1