Some optional arguments aren't always optional

[SkepticRaven]

I was running a test video where I only wanted the render (not data written to a pose file).
I got the desired output video, but it ended in an error:

TypeError: expected str, bytes or os.PathLike object, not NoneType

--
Copying the relevant stuff:

 ╭───────────────────────────────── locals ─────────────────────────────────╮ │
│ │           args = <mouse_tracking.cli.infer.fecal_boli.<locals>.Inferenc… │ │
│ │                  object at 0x7f5e32b6fbe0>                               │ │
│ │     batch_size = 1                                                       │ │
│ │          frame = None                                                    │ │
│ │ frame_interval = 1800                                                    │ │
│ │   input_source = PosixPath('/media/bgeuther/LL3_Internal/test-data/0520… │ │
│ │          model = 'fecal-boli'                                            │ │
│ │       out_file = None                                                    │ │
│ │      out_image = None                                                    │ │
│ │      out_video = PosixPath('/media/bgeuther/LL3_Internal/test-data/0520… │ │
│ │        runtime = 'pytorch'                                               │ │
│ │          video = PosixPath('/media/bgeuther/LL3_Internal/test-data/0520… │ │
│ ╰──────────────────────────────────────────────────────────────────────────╯ │

...

166 │   write_fecal_boli_data(                                             │
│   167 │   │   args.out_file,                                                 │
│   168 │   │   final_fecal_boli_detections,                                   │
│   169 │   │   final_fecal_boli_counts,  

Behavior should not be calling this func if out_file is None.

[bergsalex]

Resolved this in Bugfix/85 optional args are not always optional #105