title: Scrapy: Why do I see an error that the content is not a text
body: <p>I need your help. I use scrapy and I collect all links from website X. Then I use isinstance and check if response of href is a text or not so I have a part for html and for pdf according to isinstance result, however, sometimes I receive an info (error actually) that the content is not a text and I cannot find what is going on.</p>