fix importer to wait db close

Author: beer-1

import.go

@@ -82,19 +82,24 @@ func (i *Importer) writeNode(node *Node) error {
 	i.batchSize++
 	if i.batchSize >= maxBatchSize {
 		// Wait for previous batch.
-		var err error
 		if i.inflightCommit != nil {
-			err = <-i.inflightCommit
+			err := <-i.inflightCommit
+			if err != nil {
+				return err
+			}
+
 			i.inflightCommit = nil
 		}
-		if err != nil {
-			return err
-		}
+
 		result := make(chan error)
 		i.inflightCommit = result
 		go func(batch store.Batch) {
-			defer batch.Close()
-			result <- batch.Write()
+			if err := batch.WriteSync(); err != nil {
+				result <- err
+				return
+			}
+
+			result <- batch.Close()
 		}(i.batch)
 		i.batch = i.tree.ndb.db.NewBatch()
 		i.batchSize = 0
@@ -223,6 +228,16 @@ func (i *Importer) Commit() error {
 		return err
 	}
 
+	// Wait for previous batch.
+	if i.inflightCommit != nil {
+		err := <-i.inflightCommit
+		if err != nil {
+			return err
+		}
+
+		i.inflightCommit = nil
+	}
+
 	err = i.batch.WriteSync()
 	if err != nil {
 		return err