fix(listener): do not send a complete response when the body fails during the early read

src/listener.ts

@@ -356,6 +356,7 @@ const responseViaResponseObject = async (
 
     const values: Uint8Array[] = []
     let done = false
+    let readError: { error: unknown } | undefined
     let currentReadPromise: Promise<ReadableStreamReadResult<Uint8Array>> | undefined = undefined
 
     if (resHeaderRecord['transfer-encoding'] !== 'chunked') {
@@ -364,9 +365,11 @@ const responseViaResponseObject = async (
       for (let i = 0; i < maxReadCount; i++) {
         currentReadPromise ||= reader.read()
         const chunk = await readWithoutBlocking(currentReadPromise).catch((e) => {
-          console.error(e)
-          done = true
+          readError = { error: e }
         })
+        if (readError) {
+          break
+        }
         if (!chunk) {
           if (i === 1) {
             // XXX: In Node.js v24, some response bodies are not read all the way through until the next task queue,
@@ -376,9 +379,7 @@ const responseViaResponseObject = async (
             continue
           }
 
-          // Error occurred or currentReadPromise is not yet resolved.
-          // If an error occurs, immediately break the loop.
-          // If currentReadPromise is not yet resolved, pass it to writeFromReadableStreamDefaultReader.
+          // currentReadPromise is not yet resolved, so pass it to writeFromReadableStreamDefaultReader.
           break
         }
         currentReadPromise = undefined
@@ -392,6 +393,14 @@ const responseViaResponseObject = async (
         }
       }
 
+      if (readError) {
+        // The body failed before anything was sent, so it must not be reported as a
+        // complete (possibly empty) response.
+        handleResponseError(readError.error, outgoing)
+        ;(outgoing as OutgoingHasOutgoingEnded)[outgoingEnded]?.()
+        return
+      }
+
       if (done && !('content-length' in resHeaderRecord)) {
         resHeaderRecord['content-length'] = values.reduce((acc, value) => acc + value.length, 0)
       }

test/listener.test.ts

@@ -166,6 +166,41 @@ describe('Invalid request', () => {
   })
 })
 
+describe('Response body errors - native Response', () => {
+  const requestListener = getRequestListener((req) => {
+    const path = new URL(req.url).pathname
+    return new GlobalResponse(
+      new ReadableStream({
+        start(controller) {
+          if (path === '/after-chunk') {
+            controller.enqueue(new TextEncoder().encode('partial'))
+          }
+          controller.error(new Error('failed'))
+        },
+      })
+    )
+  })
+  const server = createServer(requestListener)
+
+  beforeEach(() => {
+    vi.spyOn(console, 'error').mockImplementation(() => {})
+  })
+
+  afterEach(() => {
+    vi.restoreAllMocks()
+  })
+
+  it('Should not send a complete empty 200 when the body fails before its first chunk', async () => {
+    const res = await requestServer(server, { method: 'GET', path: '/' })
+    expect(res.status).toBe(500)
+  })
+
+  it('Should not send a complete partial 200 when the body fails during the early read', async () => {
+    const res = await requestServer(server, { method: 'GET', path: '/after-chunk' })
+    expect(res.status).toBe(500)
+  })
+})
+
 describe('Response headers', () => {
   const requestListener = getRequestListener(() => new Response(null), {
     hostname: 'example.com',