fix deadlock on failed cluster sync

app/app.go

@@ -35,6 +35,7 @@ func Run() {
 	cluster := Cluster{}
 	cluster.Init(client)
 	start := time.Now()
+	log.Printf("[INFO] starting cluster sync\n")
 	err := cluster.Sync()
 	if err != nil {
 		log.Printf("[Error] error encountered while syncing cluster: %s", err)

app/model.go

@@ -36,6 +36,7 @@ func (cluster *Cluster) Sync() error {
 	// get all nodes
 	nodes, err := cluster.pve.Nodes()
 	if err != nil {
+		cluster.lock.Unlock()
 		return err
 	}
 
@@ -56,6 +57,7 @@ func (cluster *Cluster) Sync() error {
 
 	err = wg.Wait()
 	if err != nil {
+		cluster.lock.Unlock()
 		return err
 	}