Quality analysis found the following errors:
### Problems
1. The API endpoint `POST /repos/{owner}/{repo}/issues` is expected to return a JSON response as mentioned in the bug report.
2. The "assignees" field in the expected JSON response should contain an array of assignees, but it currently only contains a single assignee.
3. The "closed_by" field in the expected JSON response should be null, as the issue is still open. However, it currently contains an assignee, which is incorrect.
I would recommend explicitly noting the expected and observed behavior in the bug report. For example, "The 'assignees' field should contain an array of assignees, but it currently contains a single assignee."