ERR_HTTP_HEADERS_SENT when sending FormData

[sirchnik]

What version of Elysia is running?

@elysiajs/node 1.2.5(elysia@1.2.12(@sinclair/typebox@0.34.22)(openapi-types@12.1.3)(typescript@5.7.3))(formidable@3.5.2)(ws@8.18.0)

What platform is your computer?

Linux 6.13.1-arch1-1 x86_64 unknown nodejs v23.7.0

What steps can reproduce the bug?

import { Elysia } from 'elysia';
import node from '@elysiajs/node';

export const elysiaApp = new Elysia({
	adapter: node(),
}).patch('/', () => {
	const form = new FormData();
	form.append('name', 'Sancho');
	form.append('alias', 'Don Quixote');
	return form;
});
export type ElysiaApp = typeof elysiaApp;

elysiaApp.listen(3334);
console.log('Server started at http://localhost:3334');

running fetch('localhost:3334/', {method: 'PATCH'})

What is the expected behavior?

With @hono/node-server I get FormData.

What do you see instead?

Server started at http://localhost:3334
node:_http_server:351
    throw new ERR_HTTP_HEADERS_SENT('write');
          ^

Error [ERR_HTTP_HEADERS_SENT]: Cannot write headers after they are sent to the client
    at ServerResponse.writeHead (node:_http_server:351:11)
    at eval (eval at composeErrorHandler (file:///home/nik/Projects/sw/sw-reports/node_modules/.pnpm/elysia@1.2.12_@sinclair+typebox@0.34.22_openapi-types@12.1.3_typescript@5.7.3/node_modules/elysia/dist/compose.mjs:1441:10), <anonymous>:23:5)
    at eval (eval at composeHandler (file:///home/nik/Projects/sw/sw-reports/node_modules/.pnpm/elysia@1.2.12_@sinclair+typebox@0.34.22_openapi-types@12.1.3_typescript@5.7.3/node_modules/elysia/dist/compose.mjs:1155:12), <anonymous>:9:8)
    at handle (eval at composeHandler (file:///home/nik/Projects/sw/sw-reports/node_modules/.pnpm/elysia@1.2.12_@sinclair+typebox@0.34.22_openapi-types@12.1.3_typescript@5.7.3/node_modules/elysia/dist/compose.mjs:1155:12), <anonymous>:9:35)
    at Object.mainHandler (file:///home/nik/Projects/sw/sw-reports/node_modules/.pnpm/elysia@1.2.12_@sinclair+typebox@0.34.22_openapi-types@12.1.3_typescript@5.7.3/node_modules/elysia/dist/index.mjs:560:57)
    at Server.map (eval at composeGeneralHandler (file:///home/nik/Projects/sw/sw-reports/node_modules/.pnpm/elysia@1.2.12_@sinclair+typebox@0.34.22_openapi-types@12.1.3_typescript@5.7.3/node_modules/elysia/dist/compose.mjs:1337:10), <anonymous>:21:59)
    at Server.emit (node:events:507:28)
    at parserOnIncoming (node:_http_server:1153:12)
    at HTTPParser.parserOnHeadersComplete (node:_http_common:117:17) {
  code: 'ERR_HTTP_HEADERS_SENT'
}

Additional information

No response

Have you try removing the node_modules and bun.lockb and try again yet?

yes