elaborate on error "Expected Sink"

[paperdave]

Consider this code snippet.

let leakedCtrl;
using server = Bun.serve({
  async fetch(req) {
    return new Response(new ReadableStream({
      type: "direct",
      async pull(ctrl) {
        ctrl.write('a');
        await sleep(10);
        ctrl.write('b');
        ctrl.flush();
        leakedCtrl = ctrl;
      },
    } as any));
  },
});
let response = await fetch(server.url);
expect(await response.text()).toBe('ab');
leakedCtrl.write('more');

This used to throw Expected Sink, but now throws a more accurate error message:

17 |     } as any));
18 |   },
19 | });
20 | let response = await fetch(server.url);
21 | expect(await response.text()).toBe('ab');
22 | leakedCtrl.write('more');
                ^
error: This HTTPResponseSink has already been closed. A "direct" ReadableStream terminates its underlying socket once `async pull()` returns.

Closes #10632. the author should add await, an example of this is within ssr.tsx, it uses the controller out of the scope but also contains a promise that pull returns.

This PR also fixes the bug causing this, and writes being truncated, in the bake framework for react

[robobun]

❌ @paperdave, your commit d46f780 has some failures in #6889