Crash on route handler returning SSE stream.

[lithdew]

How can we reproduce the crash?

Will attempt to make a minimal reproduction.

I have a backend and frontend. The backend serves the SSE stream via. Bun.serve which has an idleTimeout set to 255. The frontend repeatedly reconnects to the SSE stream every time it gets disconnected due to the idleTimeout.

Relevant log output

Request (0 KB) {
  method: "POST",
  url: "http://localhost:3000/api/stream",
  headers: Headers {
    "host": "localhost:3000",
    "connection": "keep-alive",
    "content-length": "247",
    "user-agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/132.0.0.0 Safari/537.36",
    "content-type": "text/plain;charset=UTF-8",
    "accept": "*/*",
    "origin": "http://localhost:3000",
    "sec-fetch-mode": "cors",
    "sec-fetch-dest": "empty",
    "referer": "http://localhost:3000/",
    "accept-encoding": "gzip, deflate, br, zstd",
    "accept-language": "en-US,en-AU;q=0.9,en;q=0.8",
    "cookie": "omitted",
    "sec-ch-ua-platform": "\"macOS\"",
    "sec-ch-ua": "\"Not A(Brand\";v=\"8\", \"Chromium\";v=\"132\", \"Google Chrome\";v=\"132\"",
    "sec-ch-ua-mobile": "?0",
    "sec-fetch-site": "same-origin",
  }
  ReadableStream {
    locked: [Getter],
    cancel: [Function],
    getReader: [Function],
    pipeTo: [Function],
    pipeThrough: [Function],
    tee: [Function],
    values: [Function],
    [Symbol(Symbol.asyncIterator)]: [Function],
  }
}
============================================================
Bun v1.2.4 (fd9a5ea6) macOS Silicon
macOS v14.5
Args: "bun" "./server.ts"
Features: Bun.stderr(2) Bun.stdin(2) Bun.stdout(2) abort_signal(19) bunfig dotenv(2) fetch(37) http_server(2) jsc spawn(3) transpiler_cache(51) tsconfig(25) tsconfig_paths napi_module_register process_dlopen(4) 
Builtins: "bun:jsc" "bun:main" "bun:sqlite" "detect-libc" "node:assert" "node:async_hooks" "node:buffer" "node:child_process" "node:constants" "node:crypto" "node:dns" "node:events" "node:fs" "node:fs/promises" "node:http" "node:https" "node:module" "node:net" "node:os" "node:path" "node:perf_hooks" "node:process" "node:querystring" "node:readline" "node:stream" "node:stream/web" "node:string_decoder" "node:tls" "node:tty" "node:url" "node:util" "node:util/types" "node:vm" "node:zlib" "node:worker_threads" "ws" "node:v8" "node:http2" 
Elapsed: 446575ms | User: 498386ms | Sys: 46963ms
RSS: 13.17GB | Peak: 15.16GB | Commit: 0.02ZB | Faults: 2848

panic(main thread): Segmentation fault at address 0x10
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

Stack Trace (bun.report)

Bun v1.2.4 (fd9a5ea) on macos aarch64 [AutoCommand]

Segmentation fault at address 0x00000010

• 2 unknown/js code
• WebCore::structuredCloneForStream
• 3 unknown/js code
• llint_call_javascript
• JSC::Interpreter::executeCall
• JSC::runJSMicrotask
• JSC::VM::drainMicrotasks

Features: transpiler_cache, tsconfig, tsconfig_paths, napi_module_register, process_dlopen, Bun.stderr, Bun.stdin, Bun.stdout, abort_signal, bunfig, dotenv, fetch, http_server, jsc, spawn

_{Sentry Issue: BUN-DTF}