test if in nbdev_repo & improve `nbdev_export` err message #1246

	name: CI
	on:
	workflow_dispatch:
	pull_request:
	push:
	branches: [master]

	jobs:
	test:
	strategy:
	fail-fast: true
	matrix:
	os: [ubuntu, macos]
	version: ["3.8", "3.9", "3.10", "3.11"]
	runs-on: ${{ matrix.os }}-latest
	steps:
	- uses: fastai/workflows/nbdev-ci@master
	with:
	version: ${{ matrix.version }}
	pre: 1
	- name: test docs build
	if: ${{ (github.event_name == 'pull_request' \|\| github.event_name == 'workflow_dispatch') && matrix.version == '3.9' && matrix.os == 'ubuntu' }}
	run: \|
	set -ux
	wget -q $(curl https://latest.fast.ai/pre/quarto-dev/quarto-cli/linux-amd64.deb)
	sudo dpkg -i quarto*.deb
	nbdev_docs
	if [ -f "_docs/index.html" ]; then
	echo "docs built successfully."
	else
	echo "index page not found in rendered docs."
	ls -la
	ls -la _docs
	exit 1
	fi

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