Avoid assertion violation in unbind_to

* src/eval.c (unbind_to) <SPECPDL_LET>: Avoid assertion violation
if we get here with an object that is not a symbol.  (Bug#14412)

1 files changed, 8 insertions, 4 deletions

diff --git a/src/eval.c b/src/eval.c
index d04796abc3a..571681c318f 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -3196,11 +3196,15 @@ unbind_to (ptrdiff_t count, Lisp_Object value)
           { /* If variable has a trivial value (no forwarding), we can
                just set it.  No need to check for constant symbols here,
                since that was already done by specbind.  */
-            struct Lisp_Symbol *sym = XSYMBOL (specpdl_symbol (specpdl_ptr));
-            if (sym->redirect == SYMBOL_PLAINVAL)
+            Lisp_Object symbol = specpdl_symbol (specpdl_ptr);
+            if (SYMBOLP (symbol))
               {
-                SET_SYMBOL_VAL (sym, specpdl_old_value (specpdl_ptr));
-                break;
+                struct Lisp_Symbol *sym = XSYMBOL (symbol);
+                if (sym->redirect == SYMBOL_PLAINVAL)
+                  {
+                    SET_SYMBOL_VAL (sym, specpdl_old_value (specpdl_ptr));
+                    break;
+                  }
               }
             else
               { /* FALLTHROUGH!!