possible panic when trying index join with fixcontrol#44855 enabled

[winoros]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

create table t(a int);
create table t1(a int primary key, b int, index idx(b));
set tidb_opt_fix_control='44855:on';
explain select /*+ inl_join(t1), use_index(t1, idx) */ * from t join t1 on t.a = t1.a and t1.b = 123;

2. What did you expect to see? (Required)

run successfully.

3. What did you see instead (Required)

the session panicked.

4. What is your TiDB version? (Required)

current master