Fix premature close with chunked transfer encoding (Node 10+) and for async iterators in Node 12

[tekwiz]

What is the purpose of this pull request?

• Documentation update
• Bug fix
• New feature
• Other, please explain:

What changes did you make? (provide an overview)

re. 47b00e1: For responses using chunked Transfer-Encoding without a Content-Length, this adds a check at the socket's close event to verify that the last bytes received were the final chunk bytes, i.e. 0\r\n. If not, it creates a Premature close error and sends it to response.body.destroy(). Certain network errors evidently bypass the HTTP parser's error handling resulting in silent failures. @davidje13 confirmed fix in #739 #739 (comment).

re. 13cdcf3: Before Node.js 14, pipeline() does not fully support async iterators and does not always properly handle when the socket close/end events are out of order. This fix emits a Premature close error if the socket's readable end event occurs before the writable close event.

re. 9cf8c18: Usage of async iterators for both Node.js 12 and 14 is added to the README.

Which issue (if any) does this pull request address?

#739 #766 #968 #1055 #1056 and possibly #736

Is there anything you'd like reviewers to know?

[oed]

Very excited for this fix! 😄

[tekwiz]

@davidje13 @xxczaki @Richienb I'm seeing anecdotal evidence from multiple sources that this change fixes a large set of issues with stalling requests. I think it would be beneficial to get your reviews so we can merge and release an updated beta.

[oed]

Hey @tekwiz is there a plan to release this bugfix in a new 2.x.x release? Still waiting for a resolution of the issue that this fixes!

[ran-kalir]

are these changes released to 3.x.x? i see the changes in master but when i run npm i node-fetch@next i cant find them in the node_modules.

[xxczaki]

@ran-kalir @oed I will release 3.0.0-beta.10 once #1141 is merged 😄

[xxczaki]

(...) is there a plan to release this bugfix in a new 2.x.x release? Still waiting for a resolution of the issue that this fixes!

cc @bitinn - what do you think? sorry for the ping

@oed No, because this PR was made in the v3 branch.

[oed]

Ok, that's unfortunate. When is v3 slated for release? Or any way to backport this fix?

[xxczaki]

@oed The next beta version (3.0.0-beta.10) will be released once #1141 is merged. When it comes to the stable v3 release, it should happen later this year. I'm not sure about backporting this fix and releasing yet another v2 release - would like to hear thoughts from @node-fetch/core.

[stbrody]

Hey @xxczaki, any update on getting this backported to v2? This is causing major problems for us that is getting in the way of our product launch. (see #1055 and ipfs/js-ipfs#3465 which inspired it)

CC @oed @Gozala

[gr2m]

@stbrody can you send a pull request agains the v2 branch?