fix(odc-cli): report the status for an error response with an empty body

[jay23606]

Fixes #1779

Summary

• `HttpResponse.to_json` merged the body into the output with `props.update(**self.data)` on a non-2xx status. An empty error body is stored as `data=None`, so the CLI crashed with `TypeError: dict.update() argument after ** must be a mapping, not NoneType`.
• When the error body is not an object, the output now carries the `statusCode`. Object bodies are merged as before.

Test

• `cli/` has no test harness, and AGENTS.md says nothing checks it on a pull request, so I verified it by loading the script directly:
  • `HttpResponse(data=None, status=502).to_json(include_data=False)` gives `{"statusCode": 502}`. The original script raises the `TypeError`.
  • An object error body still merges its fields as before.
• Not run: the rest of the repo's checks, which do not cover `cli/`.

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