Mypy lint pass fails with Furo dev install on Ubuntu

[john-hen]

When running nox -s lint on Ubuntu, the mypy pass fails with error Item "Builder" of "Optional[Builder]" has no attribute "highlighter".

I'm on Ubuntu 20.04 (LTS), Python 3.8.10, and followed the development workflow for Furo as described in the documentation. NodeJS was installed via apt. It is version 12, just as the Furo docs say. The latest commit, as of this writing, is f209987.

This is the output of my console session:

~/temp$ node --version
v12.22.7

~/temp$ npm --version
6.14.15

~/temp$ git clone https://github.com/pradyunsg/furo.git
Cloning into 'furo'...
remote: Enumerating objects: 23666, done.
remote: Counting objects: 100% (5722/5722), done.
remote: Compressing objects: 100% (1128/1128), done.
remote: Total 23666 (delta 3242), reused 5225 (delta 2874), pack-reused 17944
Receiving objects: 100% (23666/23666), 61.57 MiB | 11.90 MiB/s, done.
Resolving deltas: 100% (13011/13011), done.

~/temp$ cd furo

~/temp/furo$ npm install
npm WARN read-shrinkwrap This version of npm is compatible with lockfileVersion@1,
but package-lock.json was generated for lockfileVersion@2. I'll try to do my
best with it!
npm WARN furo No repository field.
npm WARN furo No license field.

added 230 packages from 202 contributors and audited 230 packages in 13.126s

37 packages are looking for funding
  run `npm fund` for details

found 0 vulnerabilities

~/temp/furo$ pip install nox
Collecting nox
  Using cached nox-2021.10.1-py3-none-any.whl (49 kB)
Collecting argcomplete<2.0,>=1.9.4
  Using cached argcomplete-1.12.3-py2.py3-none-any.whl (38 kB)
Collecting virtualenv>=14.0.0
  Using cached virtualenv-20.10.0-py2.py3-none-any.whl (5.6 MB)
Requirement already satisfied: py<2.0.0,>=1.4.0 in /home/user/.local/lib/python3.8/site-packages (from nox) (1.10.0)
Collecting colorlog<7.0.0,>=2.6.1
  Using cached colorlog-6.6.0-py2.py3-none-any.whl (11 kB)
Requirement already satisfied: packaging>=20.9 in /home/user/.local/lib/python3.8/site-packages (from nox) (20.9)
Collecting distlib<1,>=0.3.1
  Using cached distlib-0.3.3-py2.py3-none-any.whl (496 kB)
Collecting platformdirs<3,>=2
  Using cached platformdirs-2.4.0-py3-none-any.whl (14 kB)
Collecting filelock<4,>=3.2
  Using cached filelock-3.4.0-py3-none-any.whl (9.8 kB)
Collecting backports.entry-points-selectable>=1.0.4
  Using cached backports.entry_points_selectable-1.1.1-py2.py3-none-any.whl (6.2 kB)
Requirement already satisfied: six<2,>=1.9.0 in /usr/lib/python3/dist-packages (from virtualenv>=14.0.0->nox) (1.14.0)
Requirement already satisfied: pyparsing>=2.0.2 in /home/user/.local/lib/python3.8/site-packages (from packaging>=20.9->nox) (2.4.7)
Installing collected packages: argcomplete, distlib, platformdirs, filelock, backports.entry-points-selectable, virtualenv, colorlog, nox
Successfully installed argcomplete-1.12.3 backports.entry-points-selectable-1.1.1 colorlog-6.6.0 distlib-0.3.3 filelock-3.4.0 nox-2021.10.1 platformdirs-2.4.0 virtualenv-20.10.0

~/temp/furo$ nox -s lint
nox > Running session lint
nox > Creating virtual environment (virtualenv) using python3 in .nox/lint
nox > python -m pip install pre-commit
nox > pre-commit run --all-files
[INFO] Initializing environment for https://github.com/pre-commit/mirrors-prettier.
[INFO] Initializing environment for https://github.com/pre-commit/mirrors-prettier:prettier@2.5.0.
[INFO] Initializing environment for https://github.com/psf/black.
[INFO] Initializing environment for https://github.com/asottile/blacken-docs.
[INFO] Initializing environment for https://github.com/asottile/blacken-docs:black==21.8b0.
[INFO] Initializing environment for https://github.com/PyCQA/isort.
[INFO] Initializing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Initializing environment for https://github.com/PyCQA/flake8.
[INFO] Initializing environment for https://github.com/pre-commit/mirrors-mypy.
[INFO] Initializing environment for https://github.com/pre-commit/mirrors-mypy:types-docutils.
[INFO] Initializing environment for https://github.com/PyCQA/pydocstyle.
[INFO] Installing environment for https://github.com/pre-commit/mirrors-prettier.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/psf/black.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/asottile/blacken-docs.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/PyCQA/isort.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/pre-commit/pre-commit-hooks.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/PyCQA/flake8.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/pre-commit/mirrors-mypy.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
[INFO] Installing environment for https://github.com/PyCQA/pydocstyle.
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
prettier.................................................................Passed
black....................................................................Passed
blacken-docs.............................................................Passed
isort....................................................................Passed
Check builtin type constructor use.......................................Passed
Check for added large files..............................................Passed
Check for case conflicts.................................................Passed
Check Toml...............................................................Passed
Check Yaml...............................................................Passed
Debug Statements (Python)................................................Passed
Fix End of Files.........................................................Passed
Forbid new submodules....................................................Passed
Trim Trailing Whitespace.................................................Passed
flake8...................................................................Passed
mypy.....................................................................Failed
- hook id: mypy
- exit code: 1

src/furo/__init__.py:236: error: Item "Builder" of "Optional[Builder]" has no attribute "highlighter"
src/furo/__init__.py:236: error: Item "None" of "Optional[Builder]" has no attribute "highlighter"
Found 2 errors in 1 file (checked 3 source files)

pydocstyle...............................................................Passed
nox > Command pre-commit run --all-files failed with exit code 1
nox > Session lint failed.

Subsequently, nox -s docs-live fails with a variety of errors (webpack 5.64.0 compiled with 6 errors), one of them being Cannot find module 'sass'.

[pradyunsg]

Can you delete node_modules and try running docs-live again? The workflow instructions were out of date, and I've just updated them.

[john-hen]

Okay, docs-live works now with NodeJS 16. So that fixes the build issue. The mypy lint pass still fails, I thought that was related, but apparently can just be ignored.