AttributeError: 'NoneType' object has no attribute 'start'

[kostrykin]

I have installed nbterm 0.0.13 using pip.

I have a notebook test.ipynb which consists of a single cell (1+1).

I am trying to run the notebook in batch mode using nbterm --run test.ipynb which gives the following error:

╭─────────────────────────────── Traceback (most recent call last) ────────────────────────────────╮
│ /private/tmp/test/env/lib/python3.9/site-packages/nbterm/nbterm.py:73 in main                    │
│                                                                                                  │
│   70 │   )                                                                                       │
│   71 │   if run:                                                                                 │
│   72 │   │   assert no_kernel is not True                                                        │
│ ❱ 73 │   │   asyncio.run(nb.run_all())                                                           │
│   74 │   │   if save_path is None:                                                               │
│   75 │   │   │   directory = notebook_path.parent                                                │
│   76 │   │   │   prefix = str(directory / f"{notebook_path.stem}_run")                           │
│                                                                                                  │
│ ╭───────────────────────────── locals ─────────────────────────────╮                             │
│ │    kernel_cwd = PosixPath('.')                                   │                             │
│ │            nb = <nbterm.notebook.Notebook object at 0x102216460> │                             │
│ │     no_kernel = None                                             │                             │
│ │ notebook_path = PosixPath('test.ipynb')                          │                             │
│ │        prefix = 'Untitled'                                       │                             │
│ │           run = True                                             │                             │
│ │     save_path = None                                             │                             │
│ │          test = None                                             │                             │
│ │       version = None                                             │                             │
│ ╰──────────────────────────────────────────────────────────────────╯                             │
│                                                                                                  │
│ /opt/homebrew/Caskroom/miniforge/base/envs/kostrykin2021-m1/lib/python3.9/asyncio/runners.py:44  │
│ in run                                                                                           │
│                                                                                                  │
│   41 │   │   events.set_event_loop(loop)                                                         │
│   42 │   │   if debug is not None:                                                               │
│   43 │   │   │   loop.set_debug(debug)                                                           │
│ ❱ 44 │   │   return loop.run_until_complete(main)                                                │
│   45 │   finally:                                                                                │
│   46 │   │   try:                                                                                │
│   47 │   │   │   _cancel_all_tasks(loop)                                                         │
│                                                                                                  │
│ ╭──────────────────────────────── locals ────────────────────────────────╮                       │
│ │ debug = None                                                           │                       │
│ │  loop = <_UnixSelectorEventLoop running=False closed=True debug=False> │                       │
│ │  main = <coroutine object Notebook.run_all at 0x1021f6ac0>             │                       │
│ ╰────────────────────────────────────────────────────────────────────────╯                       │
│                                                                                                  │
│ /opt/homebrew/Caskroom/miniforge/base/envs/kostrykin2021-m1/lib/python3.9/asyncio/base_events.py │
│ :642 in run_until_complete                                                                       │
│                                                                                                  │
│    639 │   │   if not future.done():                                                             │
│    640 │   │   │   raise RuntimeError('Event loop stopped before Future completed.')             │
│    641 │   │                                                                                     │
│ ❱  642 │   │   return future.result()                                                            │
│    643 │                                                                                         │
│    644 │   def stop(self):                                                                       │
│    645 │   │   """Stop running the event loop.                                                   │
│                                                                                                  │
│ ╭─────────────────────────────────────────── locals ───────────────────────────────────────────╮ │
│ │   future = <Task finished name='Task-1' coro=<Notebook.run_all() done, defined at            │ │
│ │            /private/tmp/test/env/lib/python3.9/site-packages/nbterm/notebook.py:117>         │ │
│ │            exception=AttributeError("'NoneType' object has no attribute 'start'")>           │ │
│ │ new_task = True                                                                              │ │
│ │     self = <_UnixSelectorEventLoop running=False closed=True debug=False>                    │ │
│ ╰──────────────────────────────────────────────────────────────────────────────────────────────╯ │
│                                                                                                  │
│ /private/tmp/test/env/lib/python3.9/site-packages/nbterm/notebook.py:118 in run_all              │
│                                                                                                  │
│   115 │   │   await self.current_cell.run()                                                      │
│   116 │                                                                                          │
│   117 │   async def run_all(self):                                                               │
│ ❱ 118 │   │   await self.kd.start()                                                              │
│   119 │   │   for i in range(len(self.cells)):                                                   │
│   120 │   │   │   await self.run_cell(i)                                                         │
│   121                                                                                            │
│                                                                                                  │
│ ╭──────────────────────── locals ─────────────────────────╮                                      │
│ │ self = <nbterm.notebook.Notebook object at 0x102216460> │                                      │
│ ╰─────────────────────────────────────────────────────────╯                                      │
╰──────────────────────────────────────────────────────────────────────────────────────────────────╯
AttributeError: 'NoneType' object has no attribute 'start'

Why isn't this working as expected and what does the error mean?

[davidbrochart]

Assuming the code you want to execute is written in Python, you need to install a Python kernel. You can e.g.:

pip install ipykernel