internal/gofix and fix error wrapping (#76)

pkg/es/cluster.go

@@ -44,16 +44,14 @@ func ClusterList(conf *cfg.Config) error {
 
 	// check endpoints in parallel to speed things up
 	for name, cluster := range conf.Clusters {
-		wg.Add(1)
 
-		go func() {
-			defer wg.Done()
+		wg.Go(func() {
 			online, err := cluster.IsReachable()
 
 			mu.Lock()
 			reachable[name] = clusterReachable{reachable: online, err: err}
 			mu.Unlock()
-		}()
+		})
 	}
 
 	wg.Wait()