Merge pull request #5079 from nabenabe0928/bug/fix-return-empty-list-… #849

	name: Checks

	on:
	push:
	branches:
	- master
	pull_request: {}
	schedule:
	- cron: '0 23 * * SUN-THU'

	concurrency:
	group: ${{ github.workflow }}-${{ github.ref == 'refs/heads/master' && github.run_number \|\| github.ref }}
	cancel-in-progress: true

	jobs:
	checks:
	if: (github.event_name == 'schedule' && github.repository == 'optuna/optuna') \|\| (github.event_name != 'schedule')
	runs-on: ubuntu-latest

	steps:
	- uses: actions/checkout@v3

	- uses: actions/setup-python@v4
	with:
	python-version: 3.8

	# TODO(c-bata): Remove the version constraint on SQLAlchemy
	- name: Install
	run: \|
	python -m pip install -U pip
	pip install --progress-bar off -U .[checking]

	- name: Output installed packages
	run: \|
	pip freeze --all
	- name: Output dependency tree
	run: \|
	pip install pipdeptree
	pipdeptree

	- name: black
	run: black . --check --diff
	- name: flake8
	run: flake8 .
	- name: isort
	run: isort . --check --diff
	- name: mypy
	run: mypy .
	- name: blackdoc
	run: blackdoc . --check --diff

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