[chore] throw error if GITHUB_TOKEN env is not set #34937

	name: check-links
	on:
	push:
	branches: [ main ]
	pull_request:

	# Do not cancel this workflow on main. See https://github.com/open-telemetry/opentelemetry-collector-contrib/pull/16616
	concurrency:
	group: ${{ github.workflow }}-${{ github.head_ref \|\| github.run_id }}
	cancel-in-progress: true

	jobs:
	changedfiles:
	name: changed files
	runs-on: ubuntu-latest
	env:
	PR_HEAD: ${{ github.event.pull_request.head.sha }}
	if: ${{ github.actor != 'dependabot[bot]' }}
	outputs:
	md: ${{ steps.changes.outputs.md }}
	steps:
	- uses: actions/checkout@v4
	with:
	fetch-depth: 0
	- name: Get changed files
	id: changes
	run: \|
	echo "md=$(git diff --name-only --diff-filter=ACMRTUXB $(git merge-base origin/main $PR_HEAD) $PR_HEAD \| grep .md$ \| xargs)" >> $GITHUB_OUTPUT
	check-links:
	runs-on: ubuntu-latest
	needs: changedfiles
	if: ${{needs.changedfiles.outputs.md}}
	steps:
	- uses: actions/checkout@v4
	with:
	fetch-depth: 0

	- name: Install markdown-link-check
	run: npm install -g markdown-link-check

	- name: Run markdown-link-check
	run: \|
	markdown-link-check \
	--verbose \
	--config .github/workflows/check_links_config.json \
	${{needs.changedfiles.outputs.md}} \
	\|\| { echo "Check that anchor links are lowercase"; exit 1; }

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