`const [a, b] = await Promise.all([fn1(), fn2()])` — destructured values are dropped (undefined) when fn returns property access through async; sequential awaits work

[proggeramlug]

Symptom

This pattern, which is everywhere in node code:

const [accessToken, userPlan] = await Promise.all([
  getAccessToken(userId),
  getUserPlan(userId),
]);
if (!accessToken) return reply.status(401).send({ error: "No access token. Please re-authenticate." });

…silently produces accessToken === undefined (and the 401 path fires) under Perry, even when:

• getAccessToken is logged to be returning a 256-char string (console.log inside the function fires with length=256)
• getUserPlan returns an object whose .plan access also seems empty at the callsite
• The underlying token is unexpired (refresh path isn't taken)

Rewriting to sequential awaits with no destructuring fixes it immediately:

const accessToken = await getAccessToken(userId);  // now a real 256-char string
const userPlan = await getUserPlan(userId);

After that one change, the endpoint returns clicks: 232, impressions: 17542, daily: [...] correctly — same source, same data, same Perry version, just no Promise.all + tuple destructure.

Repro context

• Perry HEAD: 13dc587a (fix(runtime): js_async_step_chain awaits V8 Promise handles instead of passing them through as primitives (#1010))
• gscmaster-api Fastify route handler. Both fns are cross-module imports.
• getAccessToken(userId) body (simplified):

  export async function getAccessToken(userId: string): Promise<string | null> {
    const account = await queryOne<DbGoogleAccount>(
      "SELECT * FROM google_accounts WHERE user_id = ? AND is_primary = TRUE", [userId]
    );
    if (!account) return null;
    // [diagnostic logs confirmed account.access_token is 256 chars, needsRefresh=false]
    const tokenValue: string = account.access_token;
    return tokenValue;
  }

• Caller path: Promise.all([getAccessToken(userId), getUserPlan(userId)]) → both values come out undefined.
• After change to sequential await getAccessToken(userId): both values come out correct.

What I tried

1. Confirmed via console.log inside getAccessToken that it returns a 256-char string.
2. Stored the property access in a local var first (const tokenValue = account.access_token; return tokenValue;) — didn't fix it alone while still using Promise.all.
3. Replaced Promise.all with sequential awaits — fixed.

Likely shape

Probably an interaction between the Promise.all helper's array-rest gather and the async-step driver's per-call frame, where the resolved values are copied into the result array but the array slots reference frames that have already been popped — so the destructuring reads undefined NaN-box slots.

Workaround

In gscmaster-api I've audited and converted these patterns to sequential awaits:

• routes/dashboard.ts ([accessToken, userPlan])
• routes/sites.ts ([currentStats, prevStats])
• routes/notifications.ts ([preferences, planInfo], [updated, planInfo])
• lib/notifications/content-generator.ts ([currentStats, previousStats], [currentQueries, previousQueries])

Followups #1010, #1009, #1008 in the changelog look like they're in the right area. This may already be fixed in main after 13dc587a — happy to re-test if there's a newer commit you want me to try, but reporting as-of HEAD.

Environment

• Perry: 13dc587a (built today at v0.5.1004)
• Target: Ubuntu 24.04 x86_64 / glibc
• Project: gscmaster-api (Fastify + mysql2 + fetch)