RowNotFound: no rows returned by a query that expected to return at least one row

Sentry Issue: [OPSQUEUE-X](https://channable.sentry.io/issues/7649829769/?referrer=github_integration)

```
RowNotFound: no rows returned by a query that expected to return at least one row

Error in chunk completer
```

Start with the linked Sentry issue OPSQUEUE-X and trace the chunk completer entry point that produces the RowNotFound error. Determine which query unexpectedly returns no rows and establish a reproducible case or relevant diagnostic context. Done means the chunk completer no longer fails unexpectedly when that query returns no rows, with regression coverage if the repository has an applicable test location.

Vom Indexierungsmodell aus dem Issue-Text verfasst.