fix(server): update proto::h1::end_body to return Result<()>

[jxs]

No description provided.

[seanmonstar]

Ok, so I understand what is happening with the failing test now. The problem is that in some states, the response needs to close the connection when the body is finished (close-delimited). This is when there is no content-length and no transfer-encoding. In that case, it's actually correct to just "close" the writing side, instead of dying in an error.

So, it seems we'd want to identify between "closing the body at this point is an actual error" vs "closing the body just means the socket should close cleanly".

[seanmonstar]

To differentiate, we could return an enum that could be matched in the _not_eof case there.

[jxs]

updated Encoder::end to not return Err on CloseDelimited, only return Err when there's content-length left.
Updated Encoder eof tests, to match the behavior you described above: when there is no content-length and no transfer-encoding it's correct to close the writing side, so Encoder::end() should not return an Err