Fix the nil pointing issue #767

	name: Build documentation and deploy it to GitHub Pages
	on:
	push:
	branches:
	- main
	pull_request:
	branches:
	- main
	workflow_dispatch:

	# Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
	permissions:
	pages: write
	id-token: write

	# Default to bash
	defaults:
	run:
	shell: bash

	# Allow one concurrent deployment
	concurrency:
	group: "pages"
	cancel-in-progress: true

	jobs:
	# Build job
	build:
	runs-on: ubuntu-latest
	steps:
	- name: Setup Pages
	id: pages
	uses: actions/configure-pages@v3
	- name: Checkout
	uses: actions/checkout@v3
	- name: Setup python
	uses: actions/setup-python@v4
	with:
	python-version: '3.11'
	cache: 'pip'
	cache-dependency-path: ./docs/requirements.txt
	- name: Set up Node.js
	uses: actions/setup-node@v3
	with:
	node-version: 20.x
	- name: Build documentation
	run: \|
	docs/build-docs.sh
	- name: Upload artifacts
	if: ${{ github.ref == 'refs/heads/main' }}
	uses: actions/upload-pages-artifact@v1
	with:
	path: docs/build/html/
	deploy:
	environment:
	name: github-pages
	url: ${{ steps.deployment.outputs.page_url }}
	runs-on: ubuntu-latest
	needs: build
	if: github.event_name != 'pull_request'
	steps:
	- name: Deploy to GitHub Pages
	id: deployment
	if: ${{ github.ref == 'refs/heads/main' }}
	uses: actions/deploy-pages@v1

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