Fix sql-related missing Close/Err calls (#1769)

server/datastore/mysql/app_configs.go

@@ -45,8 +45,14 @@ func (d *Datastore) isEventSchedulerEnabled() (bool, error) {
 	if err != nil {
 		return false, err
 	}
+	defer rows.Close()
+
 	if !rows.Next() {
-		return false, errors.New("Error detecting MySQL event scheduler status.")
+		err := errors.New("Error detecting MySQL event scheduler status.")
+		if rerr := rows.Err(); rerr != nil {
+			err = rerr
+		}
+		return false, err
 	}
 	var value string
 	if err := rows.Scan(&value); err != nil {

server/datastore/mysql/labels.go

@@ -35,6 +35,7 @@ func (d *Datastore) ApplyLabelSpecs(specs []*fleet.LabelSpec) (err error) {
 		if err != nil {
 			return errors.Wrap(err, "prepare ApplyLabelSpecs insert")
 		}
+		defer stmt.Close()
 
 		for _, s := range specs {
 			if s.Name == "" {
@@ -324,9 +325,11 @@ func (d *Datastore) LabelQueriesForHost(host *fleet.Host, cutoff time.Time) (map
 
 		results[id] = query
 	}
+	if err := rows.Err(); err != nil {
+		return nil, errors.Wrap(err, "iterating over returned rows")
+	}
 
 	return results, nil
-
 }
 
 func (d *Datastore) RecordLabelQueryExecutions(host *fleet.Host, results map[uint]bool, updated time.Time) error {

server/datastore/mysql/queries.go

@@ -49,6 +49,7 @@ func (d *Datastore) ApplyQueries(authorID uint, queries []*fleet.Query) (err err
 	if err != nil {
 		return errors.Wrap(err, "prepare ApplyQueries insert")
 	}
+	defer stmt.Close()
 
 	for _, q := range queries {
 		if q.Name == "" {