fix: gracefully fallback to body when body_path cannot be read

[Copilot]

Problem

When using both body_path and body inputs, if the file specified in body_path doesn't exist, the action crashes with an ENOENT exception instead of falling back to the body input as documented in the README.

The README states:

💡 When providing a body and body_path at the same time, body_path will be attempted first, then falling back on body if the path can not be read from.

However, the current implementation uses readFileSync without error handling, causing the action to abort when the file is missing.

Solution

Modified the releaseBody function in src/util.ts to safely attempt reading the body_path file with proper error handling:

• Wrapped readFileSync in a try-catch block to handle file read errors (ENOENT, permission errors, etc.)
• Logs a concise warning message when fallback occurs: ⚠️ Failed to read body_path "<path>" (<error_code>). Falling back to 'body' input.
• Returns the body input as fallback when file read fails
• Returns undefined if both body_path fails and body is not provided

Example Usage

- name: Release
  uses: softprops/action-gh-release@v2
  if: startsWith(github.ref, 'refs/tags/v')
  with:
    body_path: pipeline-changes.txt  # May not exist
    body: 'Default release notes'     # Fallback if file is missing
    files: |
      App*.exe

With this fix, if pipeline-changes.txt doesn't exist, the action will use 'Default release notes' instead of crashing.

Testing

Added comprehensive test coverage:

• ✅ Falls back to body when body_path file is missing
• ✅ Returns undefined when both body_path fails and body is not provided
• ✅ Existing tests pass (body_path takes precedence when file exists)
• ✅ All 39 tests passing with full backward compatibility

Fixes the issue where missing body_path files cause action failure even when a fallback body is configured.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Missing body_path file causes abort of action even if fallback body has been set</issue_title>
<issue_description>Using:

    - name: Release
      uses: softprops/action-gh-release@v2
      if: startsWith(github.ref, 'refs/tags/v')
      with:
        body_path: pipeline-changes.txt
        body: '----'
        files: |
          App*.exe

When body_path file read is attempted (readFileSync at

action-gh-release/src/util.ts

Line 35 in 97d42c1

export const releaseBody = (config: Config): string | undefined => {

), if the file does not exist it causes an ENOENT exception and crashes the action.

Main README.md states:
💡 When providing a body and body_path at the same time, body_path will be attempted first, then falling back on body if the path can not be read from.

Any exception should be captured and the fallback body used.</issue_description>

<agent_instructions>We have a bug: when with.body_path points to a non-existent file, the Action crashes with ENOENT instead of falling back to with.body. The README promises: “When providing a body and body_path at the same time, body_path will be attempted first, then falling back on body if the path can not be read from.”

Please implement the fallback and add tests.

What to change

src/util.ts

Modify releaseBody so it safely attempts to read input_body_path.

If the read throws or returns nothing, return config.input_body.

Do not throw on ENOENT or any read error; log a concise warning instead.

Suggested shape:

import { readFileSync } from 'fs';

export const releaseBody = (config: Config): string | undefined => {
if (config.input_body_path) {
try {
const contents = readFileSync(config.input_body_path, 'utf8');
return contents;
} catch (err: any) {
console.warn(
⚠️ Failed to read body_path "${config.input_body_path}" (${err?.code ?? 'ERR'}). Falling back to 'body' input.,
);
}
}
return config.input_body;
};

Tests in tests/util.test.ts
Add coverage for the fallback behavior:

“falls back to body when body_path is missing”

assert.equal(
releaseBody({
github_ref: '',
github_repository: '',
github_token: '',
input_body: 'fallback-body',
input_body_path: 'tests/does-not-exist.txt',
input_draft: false,
input_prerelease: false,
input_files: [],
input_overwrite_files: undefined,
input_preserve_order: undefined,
input_name: undefined,
input_tag_name: undefined,
input_target_commitish: undefined,
input_discussion_category_name: undefined,
input_generate_release_notes: false,
input_make_latest: undefined,
}),
'fallback-body',
);

“returns undefined when body_path is missing and body is not provided”

assert.equal(
releaseBody({
github_ref: '',
github_repository: '',
github_token: '',
input_body: undefined,
input_body_path: 'tests/does-not-exist.txt',
input_draft: false,
input_prerelease: false,
input_files: [],
input_overwrite_files: undefined,
input_preserve_order: undefined,
input_name: undefined,
input_tag_name: undefined,
input_target_commitish: undefined,
input_discussion_category_name: undefined,
input_generate_release_notes: false,
input_make_latest: undefined,
}),
undefined,
);

(Existing tests for body_path taking precedence over body should remain green.)

Run & commit

Run: npm ci && npm test

If green, create two commits:

fix: gracefully fallback to body when body_path cannot be read

test: add fallback tests for body_path ENOENT

Finally, show me:

The diff for src/util.ts and tests/util.test.ts.

The vitest summary output.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

Fixes #664

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