If an input file is not utf-8 encoded the function readfile in fs.py will not succeed.
I have some german umlauts in my input file (ISO-8859-1 encoded)
This is a typical error message:
UnicodeDecodeError: 'utf8' codec can't decode byte 0xfc in position 304: invalid start byte
I created a patch for a new commandline option:
The default value is utf-8, due to not changing the recent behavior.
Please see and check if it works for you.