patch 8.2.3152: Vim9: accessing "s:" results in an error

Problem:    Vim9: accessing "s:" results in an error.
Solution:   Do not try to lookup a script variable for "s:". (closes #8549)
diff --git a/src/evalvars.c b/src/evalvars.c
index 66018cf..27d7328 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -2660,7 +2660,8 @@
 	}
 	else if (rettv != NULL)
 	{
-	    if (ht != NULL && ht == get_script_local_ht())
+	    if (ht != NULL && ht == get_script_local_ht()
+		    && tv != &SCRIPT_SV(current_sctx.sc_sid)->sv_var.di_tv)
 	    {
 		svar_T *sv = find_typval_in_script(tv);