Fix linter errors

Author: ionthegeek

collector/pg_stat_wal.go

@@ -103,7 +103,7 @@ func statWALQuery(columns []string) string {
 	return fmt.Sprintf("SELECT %s FROM pg_stat_wal;", strings.Join(columns, ","))
 }
 
-func (c *PGStatWALCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
+func (c *PGStatWALCollector) Update(ctx context.Context, instance *Instance, ch chan<- prometheus.Metric) error {
 	db := instance.getDB()
 
 	columns := []string{

collector/pg_stat_wal_test.go

@@ -30,7 +30,7 @@ func TestPGStatWALCollector(t *testing.T) {
 	}
 	defer db.Close()
 
-	inst := &instance{db: db}
+	inst := &Instance{db: db}
 
 	columns := []string{
 		"wal_records",      // bigint
@@ -93,7 +93,7 @@ func TestPGStatWALCollectorNullValues(t *testing.T) {
 	}
 	defer db.Close()
 
-	inst := &instance{db: db}
+	inst := &Instance{db: db}
 	columns := []string{
 		"wal_records",      // bigint
 		"wal_fpi",          // bigint