fix router panic (#1254)

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

router/default.go

@@ -368,11 +368,13 @@ func (r *router) advertiseEvents() error {
 					time.Sleep(time.Second)
 				}
 
+				if w != nil {
 					// reset
 					w.Stop()
 					w = nil
 				}
 			}
+		}
 	}()
 
 	for {
@@ -467,7 +469,9 @@ func (r *router) advertiseEvents() error {
 			a.penalty += Penalty
 			log.Debugf("Router advert %d for route %s %s event penalty: %f", hash, a.event.Route.Service, a.event.Route.Address, a.penalty)
 		case <-r.exit:
+			if w != nil {
 				w.Stop()
+			}
 			return nil
 		}
 	}
@@ -700,16 +704,15 @@ func (r *router) Stop() error {
 		// extract the events
 		r.drain()
 
+		r.sub.Lock()
 		// close advert subscribers
 		for id, sub := range r.subscribers {
 			// close the channel
 			close(sub)
-
 			// delete the subscriber
-			r.sub.Lock()
 			delete(r.subscribers, id)
-			r.sub.Unlock()
 		}
+		r.sub.Unlock()
 	}
 
 	// remove event chan