Solution example

recursiveFetch.js

const axios = require('axios')

const followIDs = async (next) => {
  if (next) {
    const nextRes = await axios({
      method: 'get',
      url: next,
      responseType: 'json'
    })
    if (nextRes.data.message) {
      return nextRes.data.message
    }
    return followIDs(nextRes.data.follow.replace('challenge', 'challenge.json'))
  }

  const res = await axios({
    method: 'get',
    url: 'https://domain.com/challenge.json',
    responseType: 'json'
  })
  return followIDs(res.data.follow.replace('challenge', 'challenge.json'))
}

followIDs()
  .then(done => console.log('TEST COMPLETE', done))
  .catch(err => console.log('TEST ANOMALY', err))