For some reason, my solution is returning null instead of the value that is stored in 's'. Instructions and code are below:

You are given a string s. Consider the following algorithm applied to this string:

Take all the prefixes of the string, and choose the longest palindrome between them. If this chosen prefix contains at least two characters, cut this prefix from s and go back to the first step with the updated string. Otherwise, end the algorithm with the current string s as a result. Your task is to implement the above algorithm and return its result when applied to string s.

test case const s = "aaacodedoc"
expected output: ""

another test case
const s = "abbab" expected output: "b"

function solution(s) {

const prefixes =[]
if(s.length === 0){
    return ""
} 

if(s.length === 1){
    return s
} 


for(let i = 0; i < 1; i++){
    for(let j = i; j < s.length; j++){
        const substr = s.substring(i, j + 1)
        prefixes.push(substr)
    }
}

const palindromes = prefixes.filter(prefix => {
    let reverse = prefix.split('').reverse().join('');
    return prefix === reverse
})

let longest = palindromes.sort(
function (a, b) {
    return b.length - a.length;
})[0];

 if(longest.length >= 2){
    s = s.substring(longest.length)
    solution(s)
 } else{
    return s; 
 }
}