From ebc2e991a909d33f4720914c08d2704ae2d3f0b2 Mon Sep 17 00:00:00 2001
From: Luiz Ferraz <luiz@lferraz.com>
Date: Mon, 7 Apr 2025 09:57:17 -0300
Subject: [PATCH 1/2] Add test for expected behavior

---
 packages/astro/test/server/middleware.test.ts | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/packages/astro/test/server/middleware.test.ts b/packages/astro/test/server/middleware.test.ts
index eff473d4401f..08dcb6112421 100644
--- a/packages/astro/test/server/middleware.test.ts
+++ b/packages/astro/test/server/middleware.test.ts
@@ -149,6 +149,49 @@ describe('sentryMiddleware', () => {
     });
   });
 
+  it('throws and sends an error to sentry if response streaming throws', async () => {
+    const captureExceptionSpy = vi.spyOn(SentryNode, 'captureException');
+
+    const middleware = handleRequest();
+    const ctx = {
+      request: {
+        method: 'GET',
+        url: '/users',
+        headers: new Headers(),
+      },
+      url: new URL('https://myDomain.io/users/'),
+      params: {},
+    };
+
+    const error = new Error('Something went wrong');
+
+    const faultyStream = new ReadableStream({
+      pull: controller => {
+        controller.error(error);
+        controller.close();
+      },
+    });
+
+    const next = vi.fn(() =>
+      Promise.resolve(
+        new Response(faultyStream, {
+          headers: new Headers({ 'content-type': 'text/html' }),
+        }),
+      ),
+    );
+
+    // @ts-expect-error, a partial ctx object is fine here
+    const resultFromNext = await middleware(ctx, next);
+
+    expect(resultFromNext?.headers.get('content-type')).toEqual('text/html');
+
+    await expect(() => resultFromNext!.text()).rejects.toThrowError();
+
+    expect(captureExceptionSpy).toHaveBeenCalledWith(error, {
+      mechanism: { handled: false, type: 'astro', data: { function: 'astroMiddleware' } },
+    });
+  });
+
   describe('track client IP address', () => {
     it('attaches client IP if `trackClientIp=true` when handling dynamic page requests', async () => {
       const middleware = handleRequest({ trackClientIp: true });

From 40731fd507b07bc762e12323afa5b06397dac5e1 Mon Sep 17 00:00:00 2001
From: Luiz Ferraz <luiz@lferraz.com>
Date: Mon, 7 Apr 2025 09:59:30 -0300
Subject: [PATCH 2/2] Implement streaming error handling

---
 packages/astro/src/server/middleware.ts | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/packages/astro/src/server/middleware.ts b/packages/astro/src/server/middleware.ts
index 6b55dbd8a976..692a8a7256a3 100644
--- a/packages/astro/src/server/middleware.ts
+++ b/packages/astro/src/server/middleware.ts
@@ -184,12 +184,18 @@ async function instrumentRequest(
 
               const newResponseStream = new ReadableStream({
                 start: async controller => {
-                  for await (const chunk of originalBody) {
-                    const html = typeof chunk === 'string' ? chunk : decoder.decode(chunk, { stream: true });
-                    const modifiedHtml = addMetaTagToHead(html);
-                    controller.enqueue(new TextEncoder().encode(modifiedHtml));
+                  try {
+                    for await (const chunk of originalBody) {
+                      const html = typeof chunk === 'string' ? chunk : decoder.decode(chunk, { stream: true });
+                      const modifiedHtml = addMetaTagToHead(html);
+                      controller.enqueue(new TextEncoder().encode(modifiedHtml));
+                    }
+                  } catch (e) {
+                    sendErrorToSentry(e);
+                    controller.error(e);
+                  } finally {
+                    controller.close();
                   }
-                  controller.close();
                 },
               });