🐛 Bug Report — Runtime APIs: `Can't read from request stream after response has been sent.` in Durable Object when `request.body` not consumed

Hey! 👋

With the following configuration...

```capnp
using Workerd = import "/workerd/workerd.capnp";

const config :Workerd.Config = (
services = [
( name = "main", worker = .worker ),
],
sockets = [
( name = "http", address = "*:8080", http = (), service = "main" ),
]
);

const worker :Workerd.Worker = (
compatibilityDate = "2023-07-24",
modules = [ ( name = "index.mjs", esModule = embed "index.mjs" ) ],
durableObjectNamespaces = [
( className = "TestObject", uniqueKey = "TestObject" )
],
durableObjectStorage = ( inMemory = void ),
bindings = [
( name = "OBJECT", durableObjectNamespace = "TestObject" ),
],
);
```

```js
// index.mjs
export class TestObject {
async fetch(request) {
const { pathname } = new URL(request.url);
if (pathname === "/1") {
return new Response(); // ✅
} else if (pathname === "/2") {
return new Response("body"); // `TypeError: Can't read from request stream after response has been sent.`
} else if (pathname === "/3") {
await request.body.pipeTo(new WritableStream());
return new Response("body"); // ✅
}
return new Response(null, { status: 404 });
}
}

export default {
async fetch(request, env, ctx) {
const id = env.OBJECT.idFromName("");
const stub = env.OBJECT.get(id);
return stub.fetch(request);
}
}
```
...`workerd` returns a 200 OK response for all paths, but logs `workerd/io/io-context.c++:380: info: uncaught exception; exception = workerd/api/global-scope.c++:81: failed: jsg.TypeError: Can't read from request stream after response has been sent.` when `--verbose` is enabled and `/2` is requested with a body (e.g. `$ curl -d 0123456789 http://127.0.0.1:8080/2`). This only reproduces in a Durable Object, and not when an empty response is returned or the body is consumed.