fix(ks): 视频不可用时 photo 为 null 导致整轮爬取崩溃

快手对已删除/私密/不存在的视频，返回的 visionVideoDetail 里 photo/author 是
null——key 存在、值是 null。而 detail.get("photo", {}) 只在 key 缺失时给默认值，
key 存在且为 null 时拿到的仍是 None，紧接着的 photo.get(...) 抛 AttributeError。
该异常不在 get_video_info_task 的 except 列表里（只 catch DataFetchError /
KeyError），会穿过 asyncio.gather 直接把整轮爬取带崩。

- core.py: 用 (x or {}) 兜住 null；photo 为空时打 WARNING 并跳过该视频，
  不再返回半残的 detail 让下游存空记录、再去下载媒体
- 新增 tests/test_kuaishou_unavailable_video.py（不发网络请求）

验证：photo=null / photo 缺失 / visionVideoDetail 缺失 均返回 None；
真实 cookie 端到端确认不可用视频被跳过、正常视频照常返回详情。

media_platform/kuaishou/core.py

@@ -237,15 +237,29 @@ class KuaishouCrawler(AbstractCrawler):
                 utils.logger.info(f"[KuaishouCrawler.get_video_info_task] Sleeping for {sleep_sec:.1f} seconds after fetching video details {video_id}")
 
                 detail = result.get("visionVideoDetail")
-                if detail:
-                    photo = detail.get("photo", {})
-                    author = detail.get("author", {})
-                    utils.logger.info(
-                        f"[KuaishouCrawler.get_video_info_task] video detail: "
-                        f"id={photo.get('id', video_id)} author={author.get('name', '')} "
-                        f"likes={photo.get('likeCount', '')} views={photo.get('viewCount', '')} "
-                        f"caption={str(photo.get('caption', ''))[:50]}"
+                if not detail:
+                    return None
+
+                # 快手对不可用视频（已删除/私密/不存在）返回的是
+                # visionVideoDetail: {photo: null, author: null}——key 在、值是 null。
+                # 注意 .get("photo", {}) 只在 key **缺失** 时给默认值，key 存在且为 null
+                # 时拿到的仍是 None，接着 .get() 就抛 AttributeError，而
+                # asyncio.gather 不会拦住它，整轮爬取会直接带崩。
+                photo = detail.get("photo") or {}
+                if not photo:
+                    utils.logger.warning(
+                        f"[KuaishouCrawler.get_video_info_task] 视频不可用"
+                        f"（photo 为空，可能已删除或私密），跳过 video_id={video_id}"
                     )
+                    return None
+
+                author = detail.get("author") or {}
+                utils.logger.info(
+                    f"[KuaishouCrawler.get_video_info_task] video detail: "
+                    f"id={photo.get('id', video_id)} author={author.get('name', '')} "
+                    f"likes={photo.get('likeCount', '')} views={photo.get('viewCount', '')} "
+                    f"caption={str(photo.get('caption', ''))[:50]}"
+                )
                 return detail
             except DataFetchError as ex:
                 utils.logger.error(

tests/test_kuaishou_unavailable_video.py

@@ -0,0 +1,128 @@
+# -*- coding: utf-8 -*-
+# Copyright (c) 2025 relakkes@gmail.com
+#
+# This file is part of MediaCrawler project.
+# Repository: https://github.com/NanmiCoder/MediaCrawler/blob/main/tests/test_kuaishou_unavailable_video.py
+# GitHub: https://github.com/NanmiCoder
+# Licensed under NON-COMMERCIAL LEARNING LICENSE 1.1
+#
+
+"""快手详情接口遇到「不可用视频」时的回归测试。
+
+回归背景：快手对已删除/私密/不存在的视频返回的是
+``visionVideoDetail: {photo: null, author: null}`` —— key 存在、值是 null。
+而 ``detail.get("photo", {})`` 只在 key **缺失** 时给默认值，key 存在且为 null
+时拿到的仍是 ``None``，紧接着的 ``photo.get(...)`` 抛 AttributeError；
+该异常不在 ``get_video_info_task`` 的 except 列表里，又会穿过
+``asyncio.gather``，把整轮爬取直接带崩。
+
+这里不发起网络请求，只用 stub client 驱动真实的任务函数。
+"""
+
+from __future__ import annotations
+
+import asyncio
+import random
+import sys
+from pathlib import Path
+from types import SimpleNamespace
+
+import pytest
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+import config  # noqa: E402
+from media_platform.kuaishou.core import KuaishouCrawler  # noqa: E402
+
+PHOTO_ID = "3x3zxz4mjrsc8ke"
+UNAVAILABLE_PHOTO_ID = "3xf8enb8dbj6uig"
+
+# 真实响应里 photo/author 为 null 的那个视频
+UNAVAILABLE_DETAIL = {
+    "visionVideoDetail": {
+        "status": 1,
+        "type": "video",
+        "author": None,
+        "photo": None,
+        "tags": [],
+    }
+}
+
+NORMAL_DETAIL = {
+    "visionVideoDetail": {
+        "status": 1,
+        "type": "video",
+        "author": {"name": "余胜军说Java"},
+        "photo": {"id": PHOTO_ID, "caption": "我教你学Python", "likeCount": 167000},
+        "tags": [],
+    }
+}
+
+
+class _StubClient:
+    def __init__(self, payload):
+        self._payload = payload
+
+    async def get_video_info(self, photo_id):  # noqa: ANN001
+        return self._payload
+
+
+def _make_crawler(payload) -> SimpleNamespace:
+    """只借 get_video_info_task 用到的 self.ks_client，不需要完整 crawler"""
+    return SimpleNamespace(ks_client=_StubClient(payload))
+
+
+@pytest.fixture(autouse=True)
+def _no_sleep(monkeypatch):
+    """去掉任务里的固定延时与随机抖动，测试不应真的等待"""
+    monkeypatch.setattr(config, "CRAWLER_MAX_SLEEP_SEC", 0)
+    monkeypatch.setattr(random, "uniform", lambda a, b: 0)
+
+
+@pytest.mark.asyncio
+async def test_unavailable_video_is_skipped_instead_of_crashing():
+    """photo 为 null 时返回 None（跳过），而不是抛 AttributeError"""
+    crawler = _make_crawler(UNAVAILABLE_DETAIL)
+
+    result = await KuaishouCrawler.get_video_info_task(
+        crawler, UNAVAILABLE_PHOTO_ID, asyncio.Semaphore(1)
+    )
+
+    assert result is None
+
+
+@pytest.mark.asyncio
+async def test_missing_photo_key_is_also_skipped():
+    """photo 字段整个缺失时同样跳过（.get 的默认值路径）"""
+    crawler = _make_crawler({"visionVideoDetail": {"status": 1, "author": None}})
+
+    result = await KuaishouCrawler.get_video_info_task(
+        crawler, UNAVAILABLE_PHOTO_ID, asyncio.Semaphore(1)
+    )
+
+    assert result is None
+
+
+@pytest.mark.asyncio
+async def test_normal_video_still_returns_detail():
+    """正常视频不受影响"""
+    crawler = _make_crawler(NORMAL_DETAIL)
+
+    result = await KuaishouCrawler.get_video_info_task(
+        crawler, PHOTO_ID, asyncio.Semaphore(1)
+    )
+
+    assert result is not None
+    assert result["photo"]["id"] == PHOTO_ID
+
+
+@pytest.mark.asyncio
+async def test_empty_vision_video_detail_returns_none():
+    """visionVideoDetail 整体缺失时返回 None"""
+    crawler = _make_crawler({})
+
+    result = await KuaishouCrawler.get_video_info_task(
+        crawler, PHOTO_ID, asyncio.Semaphore(1)
+    )
+
+    assert result is None