Command Line options should trump config file

[LeamHall]

Traceback (most recent call last):
  File "/usr/local/src/LeamHall/bookbot/bookbot.py", line 433, in <module>
    chapters, specials = parse_chapters(
                         ^^^^^^^^^^^^^^^
  File "/usr/local/src/LeamHall/bookbot/bookbot.py", line 414, in parse_chapters
    data["lines"] = lines_from_file(file)
                    ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/src/LeamHall/bookbot/bookbot.py", line 102, in lines_from_file
    with open(filename, "r", encoding="utf-8-sig") as in_f:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: 'chapters/05_10.txt'

And why that specific chapter? What about the ones prior?