Problem with spell checking

[sonofmun]

When I run the command

nidaba batch -b nlbin:threshold=0.5,zoom=0.5,escale=1.0,border=0.1,perc=80,range=20,low=5,high=90 -l tesseract -o kraken:model=migne -o kraken:model=migne-njp -o kraken:model=omnibus -p spell_check:language=polytonic_greek,filter_punctuation=False -f tei2txt -- *.png

on Homer, I get the error:

postprocessing.spell_check (2, n): AttributeError: 'list' object has no attribute 'startswith'