Generates invalid python code for seemingly correct json

Describe the bug
generator around primitives in request body fails
OpenAPI Spec File
I cannot share the full spec but this is an excempt:

    "/api/helloworlduser/{externalId}/something": {
      "patch": {
        "tags": [
          "UpdateHelloWorldUser"
        ],
        "description": "Update user",
        "operationId": "HelloWorldUserUpdate",
        "parameters": [
          {
            "name": "externalId",
            "in": "path",
            "required": true,
            "schema": {
              "type": "string"
            }
          }
        ],
        "requestBody": {
          "content": {
            "application/json": {
              "schema": {
                "type": "number",
                "format": "double",
                "nullable": true
              }
            }
          }
        },
        "responses": {
          "200": {
            "description": "OK",
            "content": {
              "application/json": {
                "schema": {
                  "$ref": "#/components/schemas/UserReadDTO"
                }
              }
            }
          }
        }
      }
    },

this generates the file:

from http import HTTPStatus
from typing import Any, cast
from urllib.parse import quote

import httpx

from ...client import AuthenticatedClient, Client
from ...types import Response, UNSET
from ... import errors

from ...models.user_read_dto import UserReadDTO
from ...types import UNSET, Unset
from typing import cast



def _get_kwargs(
    external_id: str,
    *,
    body: float | None | Unset = UNSET,

) -> dict[str, Any]:
    headers: dict[str, Any] = {}


    

    

    _kwargs: dict[str, Any] = {
        "method": "patch",
        "url": "/api/helloworlduser/{external_id}/something".format(external_id=quote(str(external_id), safe=""),),
    }

    
    else:
        _kwargs["json"] = body


    headers["Content-Type"] = "application/json"

    _kwargs["headers"] = headers
    return _kwargs



def _parse_response(*, client: AuthenticatedClient | Client, response: httpx.Response) -> UserReadDTO | None:
    if response.status_code == 200:
        response_200 = UserReadDTO.from_dict(response.json())



        return response_200

    if client.raise_on_unexpected_status:
        raise errors.UnexpectedStatus(response.status_code, response.content)
    else:
        return None


def _build_response(*, client: AuthenticatedClient | Client, response: httpx.Response) -> Response[UserReadDTO]:
    return Response(
        status_code=HTTPStatus(response.status_code),
        content=response.content,
        headers=response.headers,
        parsed=_parse_response(client=client, response=response),
    )


def sync_detailed(
    external_id: str,
    *,
    client: AuthenticatedClient | Client,
    body: float | None | Unset = UNSET,

) -> Response[UserReadDTO]:
    """  Update user

    Args:
        external_id (str):
        body (float | None | Unset):

    Raises:
        errors.UnexpectedStatus: If the server returns an undocumented status code and Client.raise_on_unexpected_status is True.
        httpx.TimeoutException: If the request takes longer than Client.timeout.

    Returns:
        Response[UserReadDTO]
     """


    kwargs = _get_kwargs(
        external_id=external_id,
body=body,

    )

    response = client.get_httpx_client().request(
        **kwargs,
    )

    return _build_response(client=client, response=response)

def sync(
    external_id: str,
    *,
    client: AuthenticatedClient | Client,
    body: float | None | Unset = UNSET,

) -> UserReadDTO | None:
    """  Update user

    Args:
        external_id (str):
        body (float | None | Unset):

    Raises:
        errors.UnexpectedStatus: If the server returns an undocumented status code and Client.raise_on_unexpected_status is True.
        httpx.TimeoutException: If the request takes longer than Client.timeout.

    Returns:
        UserReadDTO
     """


    return sync_detailed(
        external_id=external_id,
client=client,
body=body,

    ).parsed

async def asyncio_detailed(
    external_id: str,
    *,
    client: AuthenticatedClient | Client,
    body: float | None | Unset = UNSET,

) -> Response[UserReadDTO]:
    """  Update user

    Args:
        external_id (str):
        body (float | None | Unset):

    Raises:
        errors.UnexpectedStatus: If the server returns an undocumented status code and Client.raise_on_unexpected_status is True.
        httpx.TimeoutException: If the request takes longer than Client.timeout.

    Returns:
        Response[UserReadDTO]
     """


    kwargs = _get_kwargs(
        external_id=external_id,
body=body,

    )

    response = await client.get_async_httpx_client().request(
        **kwargs
    )

    return _build_response(client=client, response=response)

async def asyncio(
    external_id: str,
    *,
    client: AuthenticatedClient | Client,
    body: float | None | Unset = UNSET,

) -> UserReadDTO | None:
    """  Update user

    Args:
        external_id (str):
        body (float | None | Unset):

    Raises:
        errors.UnexpectedStatus: If the server returns an undocumented status code and Client.raise_on_unexpected_status is True.
        httpx.TimeoutException: If the request takes longer than Client.timeout.

    Returns:
        UserReadDTO
     """


    return (await asyncio_detailed(
        external_id=external_id,
client=client,
body=body,

    )).parsed

which is a complete broken file (see the else in get_kwargs).

Desktop (please complete the following information):

• OS: mac os
• Python Version: 3.14
• openapi-python-client version: 0.28.3

使用提供的 OpenAPI 片段和 openapi-python-client 0.28.3 重现该问题，然后跟踪 nullable 基本类型 schema 的 request-body 生成过程。payload 未指明任何仓库文件或测试；完成标准是生成的 endpoint 模块在语法上有效，并且能够处理基本类型 request body，而不会出现报告中所示的孤立 else。