[5pt] Bug in updated MP runner

[AliForghani-NOAA]

The updated multiprocessing (MP) runner merged last Friday through PR 1647 is causing a failure when running data/roads/pull_osm_roads.py for multiple HUCs. Command used:

python foss_fim/data/roads/pull_osm_roads.py \
  -p data/inputs/pre_clip_huc8/20250917/ \
  -o outputs/RobPR/run2 \
  -j 2 \
  -lh "21010008 10300103"

Below is the error message I get:

Note: PR 1647 was merged before review was completed: