Fail to generate recursive proof of the semaphore circuit due to a shape mismatch

[EazyReal]

I found a aggregate_signals function that compresses 2 proofs into 1.
However, when testing the function, I got an error saying that in set_proof_with_pis_target, there is a shape mismatch between the target and the actual data.
I simplified the code to a function recursive_proof that only recursively proves 1 single signal, and the error is still there.
(The error message is attached, there are some extra printed messages for debugging)

a.0.siblings len 135, 139
a.1.siblings len 13, 13
thread 'main' panicked at 'itertools: .zip_eq() reached end of one iterator before the other', /Users/maxwill/.cargo/registry/src/github.com-1ecc6299db9ec823/itertools-0.10.5/src/zip_eq_impl.rs:48:13
stack backtrace:
0: std::panicking::begin_panic
1: plonky2::fri::witness_util::set_fri_proof_target
2: plonky2::iop::witness::Witness::set_proof_with_pis_target
3: plonky2_semaphore::recursion::<impl plonky2_semaphore::access_set::AccessSet>::recursive_proof
4: recursion1::main

It would be extremely appreciated if the authors can give a hint on what is causing this issue.

Note:
To recreate the error, you can run the command
RUST_BACKTRACE=1 cargo run --release --example recursion1 -- -vv
on this branch of my cloned repo
https://github.com/EazyReal/plonky2-semaphore/tree/yt/recursion/src