老师您好，我的scrapy-redis爬虫用scrapyd部署的时候出现了一个奇怪的错误，您能否帮我看看？

这个错误在pycharm中是不会出现的，更为奇怪的是，虽然Log中打印了这个错误，可是数据依然完好的爬取了下来，并写入了mysql数据库，

错误信息如下：

2017-07-26 16:52:57 [scrapy.utils.signal] ERROR: Error caught on signal handler: <bound method FeedExporter.item_scraped of <scrapy.extensions.feedexport.FeedExporter object at 0x7f4eb1c38908>>
Traceback (most recent call last):
 File "/home/song/.virtualenvs/scrapy_py3/lib/python3.5/site-packages/twisted/internet/defer.py", line 150, in maybeDeferred
   result = f(*args, **kw)
 File "/home/song/.virtualenvs/scrapy_py3/lib/python3.5/site-packages/pydispatch/robustapply.py", line 55, in robustApply
   return receiver(*arguments, **named)
 File "/home/song/.virtualenvs/scrapy_py3/lib/python3.5/site-packages/scrapy/extensions/feedexport.py", line 224, in item_scraped
   slot.exporter.export_item(item)
 File "/home/song/.virtualenvs/scrapy_py3/lib/python3.5/site-packages/scrapy/exporters.py", line 92, in export_item
   itemdict = dict(self._get_serialized_fields(item))
 File "/home/song/.virtualenvs/scrapy_py3/lib/python3.5/site-packages/scrapy/exporters.py", line 66, in _get_serialized_fields
   field_iter = six.iterkeys(item)
 File "/home/song/.virtualenvs/scrapy_py3/lib/python3.5/site-packages/six.py", line 575, in iterkeys
   return iter(d.keys(**kw))
AttributeError: 'NoneType' object has no attribute 'keys'

每爬取一条数据，都会报一下这个错，但数据确爬下来了，我google了一下，找到了一个类似的文章，但似乎不太好借鉴。

https://stackoverflow.com/questions/40918822/python3-six-attributeerror-custom-object-has-no-attribute-items

麻烦老师帮我看看，多谢。