server: fix panic when error occures on peer intialization (#163)

If an error occurs during, peer initialization then 'p' is nil. This 
may cause a panic while accessing the peer's member 
variables.

To avoid such panics, we now omit the call to `p.Disconnect` 
and also directly access the `connmgr.ConReq` variable if it's 
non-nil.

server.go

@@ -449,10 +449,9 @@ func (s *server) peerConnected(conn net.Conn, connReq *connmgr.ConnReq, inbound
 	p, err := newPeer(conn, connReq, s, peerAddr, inbound)
 	if err != nil {
 		srvrLog.Errorf("unable to create peer %v", err)
-		if p.connReq != nil {
-			s.connMgr.Remove(p.connReq.ID())
+		if connReq != nil {
+			s.connMgr.Remove(connReq.ID())
 		}
-		p.Disconnect()
 		return
 	}