fix link panic

tunnel/default.go

@@ -225,10 +225,11 @@ func (t *tun) monitor() {
 				t.Lock()
 				for _, node := range delLinks {
 					log.Debugf("Tunnel deleting dead link for %s", node)
-					link := t.links[node]
+					if link, ok := t.links[node]; ok {
 						link.Close()
 						delete(t.links, node)
 					}
+				}
 				t.Unlock()
 			}