{
  "approach": "Add a null check in `read_black_config`: if `path_config` is `None`, return `{}` immediately instead of proceeding to parse.",
  "files_to_edit": [
    "lib/python/pyflyby/_importstmt.py"
  ],
  "finish_reason": "stop",
  "hypothesis": "The function `read_black_config` calls `parse_pyproject_toml(value)` where `value` may be `None`. This occurs because `find_pyproject_toml(root)` returns `None` when no config is found, but the caller does not guard against passing `None` to `parse_pyproject_toml`. The fix is to check if the path is `None` before calling `parse_pyproject_toml`, returning an empty dict in that case.",
  "retries": {},
  "usage": {
    "completion": 163,
    "prompt": 5735,
    "reasoning": 0
  }
}