fix(widget): guard async continuations against post-disconnect null access

[tiagozip]

What this fixes

Closes #252.

When <cap-widget> is unmounted (or remounted via a React key change) while an async proof-of-work solve or speculative redeem is in flight, disconnectedCallback → cleanup() nullifies this.#speculative before those async continuations resume. Because the cleanup also calls notify() (which resolves any pending onSettled promises), the subsequent microtasks resume with this.#speculative === null and throw:

TypeError: can't access property "state", this.#speculative is null

How I reproduced it

1. Loaded the widget in a React app.
2. Started a verification (triggering speculative solve).
3. Navigated away before verification completed — unmounting the element.
4. Observed the unhandled TypeError in the browser console.

What I changed

Added if (!this.#speculative) return; guards at every async resumption point across three methods:

• #speculativeSolveAll — after await Promise.all(...) (the batch solve), after the speculative yield setTimeout, after the while loop, and inside the per-result .then() callback.
• #speculativeRedeem — at method entry, after the instrumentation await, after the capFetch await, after .json(), and at the top of the catch block.
• solve() — in the setInterval progress callback (clears the interval and returns early), and immediately after await new Promise(resolve => this.#speculative.onSettled(resolve)).

No new fields are introduced; the existing cleanup() already nullifies #speculative, which acts as the disconnection sentinel.

Caveats / edge cases

• The solve() main path (non-speculative branch) doesn't access #speculative after its awaits, so it didn't need changes.
• The finally { this.#solving = false; } block in solve() still runs correctly on an early return.
• Existing unit tests (13/13) pass unchanged.

— Claude, on behalf of Tiago

---

Generated by Claude Code

[cloudflare-workers-and-pages]

Deploying with    Cloudflare Workers

The latest updates on your project. Learn more about integrating Git with Workers.

Status	Name	Latest Commit	Updated (UTC)
❌ Deployment failed View logs	cap	e4b0ed6	May 16 2026, 09:12 AM