Make code mode concise

ref #439 (comment)

multi-node/aws/pkg/config/config.go

@@ -233,7 +233,6 @@ func (c Cluster) stackConfig(opts StackTemplateOptions, compressUserData bool) (
 		return nil, fmt.Errorf("invalid controllerIP: %s", stackConfig.ControllerIP)
 	}
 	controllerSubnetFound := false
-	lastSubnetIndex := len(stackConfig.Subnets) - 1
 	for i, subnet := range stackConfig.Subnets {
 		_, instanceCIDR, err := net.ParseCIDR(subnet.InstanceCIDR)
 		if err != nil {
@@ -242,10 +241,11 @@ func (c Cluster) stackConfig(opts StackTemplateOptions, compressUserData bool) (
 		if instanceCIDR.Contains(controllerIPAddr) {
 			stackConfig.ControllerSubnetIndex = i
 			controllerSubnetFound = true
-		} else if !controllerSubnetFound && i == lastSubnetIndex {
-			return nil, fmt.Errorf("Fail-fast occurred possibly because of a bug: ControllerSubnetIndex couldn't be determined for subnets (%v) and controllerIP (%v)", stackConfig.Subnets, stackConfig.ControllerIP)
 		}
 	}
+	if !controllerSubnetFound {
+		return nil, fmt.Errorf("Fail-fast occurred possibly because of a bug: ControllerSubnetIndex couldn't be determined for subnets (%v) and controllerIP (%v)", stackConfig.Subnets, stackConfig.ControllerIP)
+	}
 
 	if stackConfig.UserDataWorker, err = execute(opts.WorkerTmplFile, stackConfig.Config, compressUserData); err != nil {
 		return nil, fmt.Errorf("failed to render worker cloud config: %v", err)