Program does not execute due to process_wrapper.py

[grummble-ai]

Hey,

I can start the program now, but it gets stuck in file process_wrapper.py in this line:

class ProcessWrapper:
    '''Starts a sub-process that can be used in a simple question/response pattern.'''
    process: Popen

    receive_msg_fn = lambda self, msg: print("Lua: " + msg if msg else '', end='')

    def __init__(self, debug=False):
        self.debug = debug and True

    def start(self, args: List[str], cwd=None):
        cwd = cwd or os.getcwd()
        self.process = Popen(args, stdin=PIPE, stdout=PIPE, stderr=sys.stderr, universal_newlines=True, cwd=cwd, bufsize=1)
        firstline = self.process.stdout.readline() <<<<<<< 
        if firstline == '': raise EOFError("Unable to start subprocess")
        if self.debug: print('===', firstline)

It doesn't throw any error, but the program simply does not continue. Do have any ideas why this might happen?