fixes the failed_ids being overwritten when space was exhausted (we still want to return the other ids that could have failed before we ran out of space) and adds a respective test
cleans up some docstrings and tests
adds an indicator of failed ID count to the download progress bar.
A couple of small fixes and updates:
failed_ids
being overwritten when space was exhausted (we still want to return the other ids that could have failed before we ran out of space) and adds a respective test