[2.0 / next] SSR: a boundary that fails through an async read renders no error fallback outside server-component scope, and hydration asks again #4287

// ms: when the read rejects — 200 (default) is after the shell has flushed, 1 is before.
import { createMemo, Loading, Errored, createComponent, runInServerComponentScope } from "solid-js";
import { renderToStream, ssr, escape, markSafeError } from "@solidjs/web";
const mode = process.argv[2] ?? "client"; const ms = Number(process.argv[3] ?? 200);
let reject; const p = new Promise((_, j) => (reject = j)); p.catch(() => {});
function App() {
  const user = createMemo(() => p);
  return ssr(["<main>", "</main>"], createComponent(Errored, {
    fallback: e => ssr(["<p>failed: ", "</p>"], escape(e().message)),
    get children() { return createComponent(Loading, { fallback: ssr(["<p>loading</p>"]), get children() { return ssr(["<p>", "</p>"], () => escape(user().name)); } }); },
  }));
}
const view = () => createComponent(App, {});
renderToStream(mode === "server-component" ? () => runInServerComponentScope(view) : view)
  .pipe({ write: c => console.log(c.replace(/<script>[\s\S]*?<\/script>/g, "")), end() {} });
setTimeout(() => reject(markSafeError(new Error("no user 7"))), ms);   // marked safe: a failure the client may see

import { createMemo } from "solid-js";
export function App(props) {
  const user = createMemo(() => props.ask("u"));
  return <Errored fallback={e => <p>failed: {e().message}</p>}>
    <Loading fallback={<p>loading</p>}><p>{user()}</p></Loading>
  </Errored>;
}

// The server's read fails after the shell (a safe error, so the client may see it); the stream sends an empty fragment
// and the error. Then the client hydrates. Expected: "failed: no user", the server's answer used, not asked again.
import { markSafeError } from "@solidjs/web";
import { harness, wait } from "../_hydrate.mjs";
let reject;
const h = await harness(new URL(".", import.meta.url).pathname, () => new Promise((_, j) => { reject = j; }));
const page = await h.open("hydrate");
const show = async label => console.log(label.padEnd(26), JSON.stringify(await page.evaluate(() => window.repro.text())));
await show("shell");
reject(markSafeError(new Error("no user"))); await wait(100);
await show("the read fails (streamed)");
await page.evaluate(() => window.repro.start("hydrate")); await wait(100);
await show("hydrated");
console.log("asked on the client:".padEnd(26), JSON.stringify(await page.evaluate(() => window.repro.asked())), "(one is the trace Solid runs under a mocked fetch; expected: the server's error, no new question)");
await h.close();