"Error: Not Found" if push event's `before` commit is `0000000000000000000000000000000000000000`

[douglascayers]

Scenario

When configured to run on a push event and the GitHub's context.payload.before commit is 0000000000000000000000000000000000000000 (meaning there was no prior commit) then the action fails with error Error: Not Found.

The error is raised by util.js by determineModifiedFiles(..) function when it invokes octokit.rest.repos.compareCommitsWithBasehead(..)

https://github.com/pmd/pmd-github-action/blob/main/lib/util.js#L143

Config File

# .github/workflows/pmd.yml
name: Run PMD

on:
    push:
        branches:
            - my-branch
        paths:
            - my-folder

jobs:
    build:
        name: Run PMD
        runs-on: self-hosted
        steps:
            - name: Checkout repository
              uses: actions/checkout@v3

            - name: Run Apex Rules
              uses: pmd/pmd-github-action@v1
              with:
                  rulesets: rulesets/PMD/apex-rules-github.xml
                  sourcePath: my-folder
                  analyzeModifiedFilesOnly: true
                  createGitHubAnnotations: true

Expected Result

• PMD to not perform a diff comparison because there is no prior commit.
• PMD to identify the list of files included in the commit for the given source path.

Example using Git:

$ git diff-tree --no-commit-id --name-only --diff-filter=AM -r <commit>
index.html
my-folder/some-file.java

Example using Octokit

const response = await octokit.rest.repos.getCommit({
    ...context.repo,
    ref: eventData.after,
});
console.log(response);

---

{
  status: 200,
  url: 'https://api.github.com/repos/my-org/my-repo/commits/65a6b28ce342017b77bde00498434386961cdff7',
  headers: {
    ...
  },
  data: {
    sha: '65a6b28ce342017b77bde00498434386961cdff7',
    node_id: 'C_kwDOFndAydoAKDY1YTZiMjhjZTM0MjAxN2I3N2JkZTAwNDk4NDM0Mzg2OTYxY2RmZjc',
    commit: {
      ...
    },
    url: '...',
    html_url: '...',
    comments_url: '...',
    author: {
      ...
    },
    committer: {
      ...
    },
    parents: [ { ... } ],
    stats: { total: 40, additions: 36, deletions: 4 },
    files: [
        {
            sha: '4b38cfc1be0f3290f3340093825b6bbc48fd69b4',
            filename: 'index.html',
            status: 'modified',
            additions: 9,
            deletions: 1,
            changes: 10,
            blob_url: '...',
            raw_url: '...',
            contents_url: '...',
            patch: '...'
        },
        {
            sha: '565abd034c00e10add52d15cfe478f5bee3fe1da',
            filename: 'my-folder/my-file.java',
            status: 'modified',
            additions: 9,
            deletions: 1,
            changes: 10,
            blob_url: '...',
            raw_url: '...',
            contents_url: '...',
            patch: '...'
        }
    ]
  }
}

Actual Result

• Action fails with the following error

##[debug]finished caching tool
Using PMD 6.49.0 from cached path /home/docker/actions-runner/_work/_tool/pmd/6.49.0/x64
Determining modified files in my-folder...
##[debug]Push on refs/heads/my-branch: 0000000000000000000000000000000000000000...c46068a4fd0827f6c4365d24c02c1bc44707287a
Error: Not Found
##[debug]Node Action run completed with exit code 1

Workaround

• Push another commit to the branch