Changes the `Read` and `Write` error handling logic to return the original error while closing the connection. We still skip calling `handleEOF` if already closing the connection. Fixes the flaky `TestCloseWhileWriting` and `TestCloseWhileReading` tests. Co-authored-by: Sebastiaan van Stijn <github@gone.nl> Signed-off-by: Laura Brehm <laurabrehm@hey.com>