help-follow-symbol now complains if no symbol found (bug#38248)

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

* etc/NEWS: Document it.

Author: lektu

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.
+
 
 * Lisp Changes in Emacs 27.1
 

lisp/help-mode.el

@@ -749,10 +749,11 @@ Show all docs for that symbol as either a variable, function or face."
 	    (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? "))