Structured JSON logs with Error object show as empty object literal on Cloudflare dashboard despite having data

### What versions & operating system are you using?

Wrangler 4.33.1, Node 22.19.0, macOS 15.6.1

### Please provide a link to a minimal reproduction

_No response_

### Describe the Bug

I am using custom structured JSON logs in my code: https://developers.cloudflare.com/workers/observability/logs/workers-logs/#custom-logs

I am seeing a difference in the structured JSON logs output from `wrangler dev` and what appears in the Observability section of my Cloudflare dashboard.

`Error` object instances appear nicely formatted in the local console, but on the dashboard appear as `{}`. I know for sure there is content since I stringily the error object and log it later.

```ts
} catch (e) {
console.error('Segment failed:', {runId, segmentId: segment.id, error: e});
const error = stringifyError(e, 1000);
```

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Wrangler Dev:

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Dashboard:

(note: $workers.truncated is false)

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Is this data actually in the logs and simply not displayed in the dashboard, or is there some logic that would compact the output in the dashboard?

### Please provide any relevant error logs

_No response_