nitrojs / nitrojs/nitro

Build file with bun preset crashes when using SSE

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bug v2
Dominant language
TypeScript
Stars
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Forks
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Avg merge
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Merged PRs (30d)
40

Description

Environment

nitropack: 2.12.8
bun: 1.3.1

Reproduction

Commands:

bun init
Select a project template: Library
bun add nitropack

Files:
Delete index.ts

Create nitro.config.ts:

export default defineNitroConfig({
    preset: "bun",
});

Create routes/index.ts:

export default defineEventHandler(() => {
    return `
    <!DOCTYPE html>
    <html>
      <head>
        <title>Nitro SSE Demo</title>
      </head>
      <body>
        <script>
          new EventSource('/events');
        </script>
      </body>
    </html>
  `;
});

Create routes/events.ts:

export default defineEventHandler(async (event) => {
    const eventStream = createEventStream(event);

    const interval = setInterval(async () => {
        await eventStream.push(`Message @ ${new Date().toLocaleTimeString()}`);
    }, 1000);

    eventStream.onClosed(async () => {
        clearInterval(interval);
        await eventStream.close();
    });

    return eventStream.send();
});

Commands:

bunx nitro build
bun run .output/server/index.mjs

Visit: http://localhost:3000/

Look into the console:

error: undefined
undefined
error: undefined
undefined
Describe the bug

When using Nitro's SSE feature & bun, it crashes. Works in dev mode, only applied to the builded .mjs file.
Also works when using node instead of bun.

Additional context

Sometimes works, when then reloading the page or re-open it, it crashes.

Logs
error: undefined
undefined
error: undefined
undefined

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the failure with nitro.config.ts, routes/index.ts, routes/events.ts, and the commands bunx nitro build followed by bun run .output/server/index.mjs. Compare the built .output/server/index.mjs with dev mode and the Node runtime, then trace Bun preset handling around the SSE event stream; done means the built Bun server serves /events reliably without the logged errors.

Written by the indexing model from the issue text.

Assessment

Tech stack
bun, typescript
Domain
backend, build-system
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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