master a1e454d: Protect add-variable-watcher from incorrect usage

[Eli Zaretskii]

branch: master
commit a1e454d6df011f2a02d3b4900dd33d1d3717c6ef
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Protect add-variable-watcher from incorrect usage
    
    * src/data.c (Fadd_variable_watcher): Avoid crashes if SYMBOL
    isn't.  (Bug#47462)
---
 src/data.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/data.c b/src/data.c
index 0fa491b..3667b03 100644
--- a/src/data.c
+++ b/src/data.c
@@ -1589,6 +1589,7 @@ All writes to aliases of SYMBOL will call WATCH-FUNCTION 
too.  */)
   (Lisp_Object symbol, Lisp_Object watch_function)
 {
   symbol = Findirect_variable (symbol);
+  CHECK_SYMBOL (symbol);
   set_symbol_trapped_write (symbol, SYMBOL_TRAPPED_WRITE);
   map_obarray (Vobarray, harmonize_variable_watchers, symbol);