title: GitHub Action: Invalid environment variable format
body: <p>I have a problem with Github action. After I configured <code>README.md</code> over web browser after that GitHub action throw error:</p>
  <pre><code>Run export BUILD_VERSION=$(grep version package.json | awk -F \&quot; '{print $4}')
    export BUILD_VERSION=$(grep version package.json | awk -F \&quot; '{print $4}')
    echo &quot;BUILD_VERSION=$BUILD_VERSION&quot; &gt;&gt; $GITHUB_ENV
    shell: /usr/bin/bash -e {0}
  Error: Unable to process file command 'env' successfully.
  Error: Invalid environment variable format 'Indicate that a variable can have the value `null`. Null-Safety is default from version **2.12.0** in the Dart language.'
  </code></pre>
  <p>The variable format is a text from the <code>README.md</code> and now no matter how I edit it always throws an error with the old error text. I tried to google it but not found any similar solution.</p>
  <ul>
  <li>Current mine variable format</li>
  </ul>
  <blockquote>
  <p>Null-Safety is enabled as default and it will indicate that a variable may have the value null. Required in the new Dart language from version 2.12.0.</p>
  </blockquote>
  <p>My workflow file:</p>
  <pre><code>name: release master branch
  
  on:
    push:
      branches:
        - master
  
  jobs:
    build:
      name: build
      runs-on: ubuntu-latest
      steps:
        - name: Checkout Repo
          uses: actions/checkout@master
        - name: install dependencies
          run: npm install
        - name: install vsce
          run: sudo npm install -g vsce
        - name: extract version number
          run: |
            export BUILD_VERSION=$(grep version package.json | awk -F \&quot; '{print $4}')
            echo &quot;BUILD_VERSION=$BUILD_VERSION&quot; &gt;&gt; $GITHUB_ENV
        - name: package the extension
          run: vsce package
        - name: release package to github repo
          uses: marvinpinto/action-automatic-releases@latest
          with:
            repo_token: '${{ secrets.GITHUB_TOKEN }}'
            automatic_release_tag: master-v${{ env.BUILD_VERSION }}
            prerelease: true
            title: 'Json to Dart Extension master-v${{ env.BUILD_VERSION }}'
            files: |
              ./json-to-dart-${{ env.BUILD_VERSION }}.vsix
  </code></pre>
  <p>By adding paths ignore do not resolve it.</p>
  <pre><code>on:
    push:
      branches:
        - master
      paths-ignore:
        - '**/README.md'
  </code></pre>
  <p>The full code is public; you can find it at <a href="https://github.com/hiranthaR/Json-to-Dart-Model" rel="nofollow noreferrer">https://github.com/hiranthaR/Json-to-Dart-Model</a></p>
  <p>Partial log:</p>
  <pre><code>...
  2021-08-02T19:38:38.3085331Z ##[group]Run sudo npm install -g vsce
  2021-08-02T19:38:38.3086141Z [36;1msudo npm install -g vsce[0m
  2021-08-02T19:38:38.3129504Z shell: /usr/bin/bash -e {0}
  2021-08-02T19:38:38.3129978Z ##[endgroup]
  2021-08-02T19:38:42.3974877Z /usr/local/bin/vsce -&gt; /usr/local/lib/node_modules/vsce/out/vsce
  2021-08-02T19:38:42.4134841Z + vsce@1.96.1
  2021-08-02T19:38:42.4135550Z added 73 packages from 42 contributors in 3.582s
  2021-08-02T19:38:42.4443780Z ##[group]Run export BUILD_VERSION=$(grep version package.json | awk -F \&quot; '{print $4}')
  2021-08-02T19:38:42.4444834Z [36;1mexport BUILD_VERSION=$(grep version package.json | awk -F \&quot; '{print $4}')[0m
  2021-08-02T19:38:42.4445782Z [36;1mecho &quot;BUILD_VERSION=$BUILD_VERSION&quot; &gt;&gt; $GITHUB_ENV[0m
  2021-08-02T19:38:42.4489050Z shell: /usr/bin/bash -e {0}
  2021-08-02T19:38:42.4489590Z ##[endgroup]
  2021-08-02T19:38:42.4690016Z ##[error]Unable to process file command 'env' successfully.
  2021-08-02T19:38:42.4703378Z ##[error]Invalid environment variable format 'Indicate that a variable can have the value `null`. Null-Safety is default from version **2.12.0** in the Dart language.'
  2021-08-02T19:38:42.4890985Z Post job cleanup.
  ...
  </code></pre>