Fix a bug where no error message was set for peer disconnects.
Fix a bug where no error message was set for peer disconnects.

TEST=Manual. AFAIK, the cause of this error is the socket receiving a TCP RST from it's peer and, AFAIK, I can't do that from Dart.
Bug:  https://github.com/dart-lang/sdk/issues/47766
Change-Id: Ia423ee951b96bdb140c321fbc87b6bd59e39d84d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/221222
Reviewed-by: Alexander Aprelev <dfb74c35a357c2059971a4bf7fe26b6a7c18085d@google.com>
Commit-Queue: Brian Quinlan <2ba0baab12cbdc73959f1aa8397b55b4d7de9371@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk