when:
=====
* saving "--chunk-size" portions of a file
  with "--max-concurrency" threads
* a chunk is successfully downloaded
* its size in bytes is validated
* the attempt to write the chunk to the output file fails

previously:
===========
* the strategy was to throw an Error, which:
  - discards the chunk
  - requeues the URL to download the chunk
  - attempt to redownload until either:
    * success
    * the number of failed download attempts causes an abort

now:
====
* requeue the chunk to write to the output file
* attempt to rewrite until either:
  - success
  - the number of failed write attempts causes an abort