Describe the bug

On the Schedule detail page, the browser console shows the CodeMirror crash-guard firing twice:

CodeMirror plugin crashed: TypeError: can't access property Symbol.iterator, n is undefined
    Immutable 129
    Immutable 123
    ...
    (bundle chunk DSXxv-SB.js:7:19206)

CodeMirror disables the crashing extension and the page continues to work, so the impact appears cosmetic (the JSON payload/input viewer on the schedule detail page), but the crash fires reliably on every visit to the page.

All network requests during the page load return 200 — this is purely a client-side rendering error.

To Reproduce

1. Self-hosted Temporal server 1.31.1 + ui-server v2.51.0 (also reproduced after upgrading to v2.51.1)
2. Create a schedule whose action has an input payload (ours: a cron schedule started from the TypeScript SDK, workflow input payload present)
3. Open the schedule detail page (/namespaces/{ns}/schedules/{scheduleId})
4. Open the browser console (observed in Firefox)

Expected behavior

No CodeMirror extension crash; payload viewer renders with syntax highlighting.

Environment

• Temporal UI: 2.51.0 and 2.51.1 (self-hosted ui-server, Linux amd64)
• Temporal Server: 1.31.1
• Browser: Firefox (latest)

Happy to provide the schedule JSON or a HAR trace if useful.