handle null op_next in stacked filetests

When a filetest op returns false, it skips past following ops that
are stacked filetests.  The code to do this was assuming that op_next
would always be non-null, which is not always the case, for example in
a sort comparator.  Allow for it to be null.  Fixes [perl #129347].

1 files changed, 1 insertions, 1 deletions

diff --git a/pp_sys.c b/pp_sys.c
index 7a4c4ab1ef..b078586974 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -3116,7 +3116,7 @@ S_ft_return_false(pTHX_ SV *ret) {
     PUTBACK;
 
     if (PL_op->op_private & OPpFT_STACKING) {
-        while (OP_IS_FILETEST(next->op_type)
+        while (next && OP_IS_FILETEST(next->op_type)
                && next->op_private & OPpFT_STACKED)
             next = next->op_next;
     }