Simply run the reduce.sh script from this directory like this inside the git bash shell window:

./reduce.sh

If you want to ensure a fresh copy of the langtags.json file, delete any existing copy in this folder first:

rm langtags.json
./reduce.sh

(An existing copy of langtags.json is used for processing to save download time.)

After generating a new version of the reduced-langtags.json file, it will need to be copied (or moved) to the src/components/AggregateGrid folder:

cp reduced-langtags.json ../../src/components/AggregateGrid

or

mv reduced-langtags.json ../../src/components/AggregateGrid

There is no need to use either npm or yarn as far as I can tell. Perhaps node is trying to keep up with bun?

The shell script may need to have its line endings changed if you want to run it under another shell such as the Cygwin bash shell window or the Windows Subsystem for Linux shell window.