Remove github.com/pkg/errors and replace with std library version

This is possible now that we no longer support go1.12 and brings
rclone into line with standard practices in the Go world.

This also removes errors.New and errors.Errorf from lib/errors and
prefers the stdlib errors package over lib/errors.

backend/mailru/api/helpers.go

@@ -6,11 +6,11 @@ import (
 	"bufio"
 	"bytes"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"io"
 	"time"
 
-	"github.com/pkg/errors"
 	"github.com/rclone/rclone/lib/readers"
 )
 

backend/mailru/mailru.go

@@ -3,6 +3,7 @@ package mailru
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	gohash "hash"
 	"io"
@@ -40,7 +41,6 @@ import (
 	"github.com/rclone/rclone/lib/readers"
 	"github.com/rclone/rclone/lib/rest"
 
-	"github.com/pkg/errors"
 	"golang.org/x/oauth2"
 )
 
@@ -438,7 +438,7 @@ func (f *Fs) authorize(ctx context.Context, force bool) (err error) {
 		err = errors.New("Invalid token")
 	}
 	if err != nil {
-		return errors.Wrap(err, "Failed to authorize")
+		return fmt.Errorf("Failed to authorize: %w", err)
 	}
 
 	if err = oauthutil.PutToken(f.name, f.m, t, false); err != nil {
@@ -507,7 +507,7 @@ func (f *Fs) reAuthorize(opts *rest.Opts, origErr error) error {
 func (f *Fs) accessToken() (string, error) {
 	token, err := f.source.Token()
 	if err != nil {
-		return "", errors.Wrap(err, "cannot refresh access token")
+		return "", fmt.Errorf("cannot refresh access token: %w", err)
 	}
 	return token.AccessToken, nil
 }
@@ -1196,7 +1196,7 @@ func (f *Fs) purgeWithCheck(ctx context.Context, dir string, check bool, opName
 
 	_, dirSize, err := f.readItemMetaData(ctx, path)
 	if err != nil {
-		return errors.Wrapf(err, "%s failed", opName)
+		return fmt.Errorf("%s failed: %w", opName, err)
 	}
 	if check && dirSize > 0 {
 		return fs.ErrorDirectoryNotEmpty
@@ -1300,7 +1300,7 @@ func (f *Fs) Copy(ctx context.Context, src fs.Object, remote string) (fs.Object,
 	})
 
 	if err != nil {
-		return nil, errors.Wrap(err, "couldn't copy file")
+		return nil, fmt.Errorf("couldn't copy file: %w", err)
 	}
 	if response.Status != 200 {
 		return nil, fmt.Errorf("copy failed with code %d", response.Status)
@@ -1684,7 +1684,7 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 
 			spoolFile, mrHash, err := makeTempFile(ctx, tmpFs, wrapIn, src)
 			if err != nil {
-				return errors.Wrap(err, "Failed to create spool file")
+				return fmt.Errorf("Failed to create spool file: %w", err)
 			}
 			if o.putByHash(ctx, mrHash, src, "spool") {
 				// If put by hash is successful, ignore transitive error
@@ -2318,7 +2318,7 @@ func (p *serverPool) Dispatch(ctx context.Context, current string) (string, erro
 	})
 	if err != nil || url == "" {
 		closeBody(res)
-		return "", errors.Wrap(err, "Failed to request file server")
+		return "", fmt.Errorf("Failed to request file server: %w", err)
 	}
 
 	p.addServer(url, now)