fix: pass parse errors to transform callback instead of throwing

commit-stream.js

@@ -46,7 +46,13 @@ export default function commitStream (ghUser, ghProject) {
   return new Transform({
     objectMode: true,
     transform (line, _, callback) {
-      emit(this, addLine(line))
+      let done
+      try {
+        done = addLine(line)
+      } catch (err) {
+        return callback(/** @type {Error} */ (err))
+      }
+      emit(this, done)
       callback()
     },
     flush (callback) {
@@ -73,7 +79,7 @@ export default function commitStream (ghUser, ghProject) {
     let m
 
     if (!commit) {
-      throw new Error('Something unexpected occurred')
+      throw new Error(`Unexpected line before first "commit" header: ${line}`)
     }
 
     if ((m = line.match(/^CommitDate:\s+(.*)$/)) !== null) {

test.js

@@ -233,3 +233,17 @@ test('cve id with 4 or more sequence digits', async () => {
   const commits = await toCommits(ids.flatMap(log))
   assert.deepStrictEqual(commits.map((c) => c.cveId), ids)
 })
+
+test('line before first commit header rejects pipeline', async () => {
+  await assert.rejects(toCommits(['garbage']), {
+    message: 'Unexpected line before first "commit" header: garbage'
+  })
+})
+
+test('line before first commit header emits error on write', async () => {
+  const stream = commitStream()
+  const error = once(stream, 'error')
+  stream.write('garbage')
+  const [err] = await error
+  assert.strictEqual(err.message, 'Unexpected line before first "commit" header: garbage')
+})