Thanks for the PR! Very interesting. 👀 Do you have a link to some documentation which states that the response body may be undefined in that (or some other) polyfill?

Hi@xenova, Thanks for the reply!
I couldn't find anywhere in the documentation of that polyfill, but I found a few issues (JakeChampion/fetch#1454,JakeChampion/fetch#746,JakeChampion/fetch#198 (comment)) sayingResponse.body is undefined and would unlikely be supported ever.

Another polyfillhttps://github.com/developit/unfetch saysit only supports a subset of the Response class,response.body is not included.

Thanks for the info 👍 And just for interest's sake, what environment are you running in that requires a fetch polyfill?