Error needs to be emitted if replication connections destroy with a failure

[pfrazee]

Quite related to https://github.com/joehand/hypercloud/issues/16

Turns out there are some conditions occurring which cause replication feeds to stop with an error. Replication streams should end with an error when that happens. Where-ever the replication stream is created, we need to be sure there's code listening for its end and emitting the error in the non-debug logs.

cc @mafintosh

[pfrazee]

Looks like the best way to do this is to attach to the 'error' event on hypercore-protocol instances