fix: use parent commit's tree SHA as base_tree for GitHub API createTree call

Agent-Logs-Url: https://github.com/qoomon/actions--create-commit/sessions/e7d2a904-30c4-4099-ac7e-a162a020bdca

Co-authored-by: qoomon <3963394+qoomon@users.noreply.github.com>

Author: Copilot

dist/index.js

@@ -38248,7 +38248,7 @@ async function createCommit(octokit, repository, args) {
             const chunk = commitTreeBlobs.slice(i, i + chunkSize);
             commitTreeSha = await octokit.rest.git.createTree({
                 ...repository,
-                base_tree: commitTreeSha,
+                ...(commitTreeSha !== undefined ? { base_tree: commitTreeSha } : {}),
                 tree: chunk,
             }).then(({ data }) => data.sha).finally(() => {
                 progress++;
@@ -38257,6 +38257,9 @@ async function createCommit(octokit, repository, args) {
             });
         }
     }
+    if (commitTreeSha === undefined) {
+        throw new Error('Could not determine commit tree SHA: no parent tree SHA was provided and no files were given to create a new tree');
+    }
     console.log('Creating commit...');
     const commit = await octokit.rest.git.createCommit({
         ...repository,
@@ -38381,10 +38384,13 @@ const action = () => run(async () => {
     const headCommit = await getCommitDetails('HEAD');
     const repositoryRemoteUrl = await getRemoteUrl(input.remoteName);
     const repository = parseRepositoryFromUrl(repositoryRemoteUrl);
+    const parentCommit = headCommit.parents.length > 0
+        ? await getCommitDetails(headCommit.parents[0])
+        : null;
     const githubCommit = await createCommit(octokit, repository, {
         subject: headCommit.subject,
         body: headCommit.body,
-        tree: headCommit.tree,
+        tree: parentCommit?.tree,
         parents: headCommit.parents,
         files: headCommit.files.map((file) => ({
             path: file.path,

index.ts

@@ -93,10 +93,13 @@ export const action = () => run(async () => {
   const headCommit = await getCommitDetails('HEAD')
   const repositoryRemoteUrl = await getRemoteUrl(input.remoteName)
   const repository = parseRepositoryFromUrl(repositoryRemoteUrl)
+  const parentCommit = headCommit.parents.length > 0
+      ? await getCommitDetails(headCommit.parents[0])
+      : null
   const githubCommit = await createCommit(octokit, repository, {
     subject: headCommit.subject,
     body: headCommit.body,
-    tree: headCommit.tree,
+    tree: parentCommit?.tree,
     parents: headCommit.parents,
     files: headCommit.files.map((file) => ({
       path: file.path,

lib/github.ts

@@ -63,7 +63,7 @@ export async function createCommit(
       const chunk = commitTreeBlobs.slice(i, i + chunkSize)
       commitTreeSha = await octokit.rest.git.createTree({
         ...repository,
-        base_tree: commitTreeSha,
+        ...(commitTreeSha !== undefined ? {base_tree: commitTreeSha} : {}),
         tree: chunk,
       }).then(({data}) => data.sha).finally(() => {
         progress++;
@@ -73,6 +73,10 @@ export async function createCommit(
     }
   }
 
+  if (commitTreeSha === undefined) {
+    throw new Error('Could not determine commit tree SHA: no parent tree SHA was provided and no files were given to create a new tree')
+  }
+
   console.log('Creating commit...')
   const commit = await octokit.rest.git.createCommit({
     ...repository,
@@ -119,7 +123,7 @@ export type CreateCommitArgs = {
   subject: string
   body: string
   parents: string[]
-  tree: string,
+  tree: string | undefined,
   files: {
     path: string
     mode: '100644' | '100755' | '040000' | '160000' | '120000' | string