"failed to fill whole buffer" error message when trying to deserialise an object in Rust

Question

I am trying to deserialise an object of type MembershipWitness from a [u8] submitted by the user via rest api. The input from the user is a string which contains the bytes separated by a comma, so I had to parse this string an convert it to [u8].

let mut witness_bytes: [u8; 32] = [0; 32];
let mut decoded_witness_elements = decoded_witness.split(",");
let mut k=0;
for s in decoded_witness_elements {
    witness_bytes[k] = s.parse::<u8>().unwrap();
    k=k+1;
}

let mut witness: &[u8] = &witness_bytes;
let witness_membership = <MembershipWitness<G1Affine>>::deserialize(witness).unwrap();

I am getting the following error:

thread 'tokio-runtime-worker' panicked at 'called `Result::unwrap()` on an `Err` value: IoError(Error { kind: UnexpectedEof, message: "failed to fill whole buffer" })', 

This is related to the last line of of the above code.

Please note that I am using the crate: https://crates.io/crates/vb_accumulator.

Here are some screenshots that hopefully helps in understanding the issue: