Use errors instead of golang.org/x/xerrors

stdlib/sql.go

@@ -52,6 +52,7 @@ import (
 	"context"
 	"database/sql"
 	"database/sql/driver"
+	"errors"
 	"fmt"
 	"io"
 	"math"
@@ -61,8 +62,6 @@ import (
 	"sync"
 	"time"
 
-	errors "golang.org/x/xerrors"
-
 	"github.com/jackc/pgconn"
 	"github.com/jackc/pgtype"
 	"github.com/jackc/pgx/v4"
@@ -308,7 +307,7 @@ func (c *Conn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, e
 	case sql.LevelSerializable:
 		pgxOpts.IsoLevel = pgx.Serializable
 	default:
-		return nil, errors.Errorf("unsupported isolation: %v", opts.Isolation)
+		return nil, fmt.Errorf("unsupported isolation: %v", opts.Isolation)
 	}
 
 	if opts.ReadOnly {
@@ -779,7 +778,7 @@ func ReleaseConn(db *sql.DB, conn *pgx.Conn) error {
 		fakeTxMutex.Unlock()
 	} else {
 		fakeTxMutex.Unlock()
-		return errors.Errorf("can't release conn that is not acquired")
+		return fmt.Errorf("can't release conn that is not acquired")
 	}
 
 	return tx.Rollback()