chore: improve error message when attaching with no file or annotatio… #55

	# Copyright The ORAS Authors.
	# Licensed under the Apache License, Version 2.0 (the "License");
	# you may not use this file except in compliance with the License.
	# You may obtain a copy of the License at
	#
	# http://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software
	# distributed under the License is distributed on an "AS IS" BASIS,
	# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	# See the License for the specific language governing permissions and
	# limitations under the License.

	name: release-ghcr

	on:
	push:
	tags: [v*]
	branches: [main]

	jobs:
	build:
	runs-on: ubuntu-latest
	permissions:
	contents: read
	packages: write
	steps:
	- name: Checkout
	uses: actions/checkout@v4
	- name: prepare
	id: prepare
	run: \|
	TAG=${GITHUB_REF#refs/*/} # get branch or tag as image tag
	echo "ref=ghcr.io/${{ github.repository }}:${TAG}" >> $GITHUB_OUTPUT
	- name: docker login
	uses: docker/login-action@v3
	with:
	registry: ghcr.io
	username: ${{ github.actor }}
	password: ${{ secrets.GITHUB_TOKEN }}
	- name: docker build
	run: \|
	docker buildx create --use
	docker buildx build --platform linux/amd64,linux/arm64,linux/arm/v7,linux/s390x,linux/ppc64le -t ${{ steps.prepare.outputs.ref }} --push .
	- name: clear
	if: always()
	run: \|
	rm -f ${HOME}/.docker/config.json

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