This looks very interesting, nice one. I gave it a very quick test on MacOS and FreeBSD
On Mac some of the text fields have a white background:
On both systems it creates output directories and files as shown below, the directories are actually empty and it has created the file names to include what I assume was suppose to be the directory it would have gone inside:
.\exported\blockstates\
.\exported\blockstates\\TestBlock.json
.\exported\models\block\
.\exported\models\block\\TestBlock.json
.\exported\models\item\
.\exported\models\item\\TestBlock.json
I can do some more testing if you're interested. Keep up the good work.