If isErrorClosed returns true, then the error condition can be
retrieved by this method.
true iff the connection has been closed in response to an Abort command.
true iff the connection has been fully closed in response to a
ConfirmedClose command.
true iff the connection has been closed due to an IO error.
true iff the connection has been closed by the peer; in case
keepOpenOnPeerClosed is in effect as per the Register command,
this connection’s reading half is now closed.
This is the common interface for all events which indicate that a connection has been closed or half-closed.