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/filefabric/filefabric.go

@@ -17,6 +17,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/base64"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -32,7 +33,6 @@ import (
 	"github.com/rclone/rclone/lib/encoder"
 	"github.com/rclone/rclone/lib/random"
 
-	"github.com/pkg/errors"
 	"github.com/rclone/rclone/backend/filefabric/api"
 	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/config"
@@ -267,7 +267,7 @@ func (f *Fs) readMetaDataForPath(ctx context.Context, rootID string, path string
 		"pid":  rootID,
 	}, &resp, nil)
 	if err != nil {
-		return nil, errors.Wrap(err, "failed to check path exists")
+		return nil, fmt.Errorf("failed to check path exists: %w", err)
 	}
 	if resp.Exists != "y" {
 		return nil, fs.ErrorObjectNotFound
@@ -308,7 +308,7 @@ func (f *Fs) getApplianceInfo(ctx context.Context) error {
 		"token": "*",
 	}, &applianceInfo, nil)
 	if err != nil {
-		return errors.Wrap(err, "failed to read appliance version")
+		return fmt.Errorf("failed to read appliance version: %w", err)
 	}
 	f.opt.Version = applianceInfo.SoftwareVersionLabel
 	f.m.Set("version", f.opt.Version)
@@ -349,7 +349,7 @@ func (f *Fs) getToken(ctx context.Context) (token string, err error) {
 		"authtoken": f.opt.PermanentToken,
 	}, &info, nil)
 	if err != nil {
-		return "", errors.Wrap(err, "failed to get session token")
+		return "", fmt.Errorf("failed to get session token: %w", err)
 	}
 	refreshed = true
 	now = now.Add(tokenLifeTime)
@@ -562,7 +562,7 @@ func (f *Fs) CreateDir(ctx context.Context, pathID, leaf string) (newID string,
 		"fi_name": f.opt.Enc.FromStandardName(leaf),
 	}, &info, nil)
 	if err != nil {
-		return "", errors.Wrap(err, "failed to create directory")
+		return "", fmt.Errorf("failed to create directory: %w", err)
 	}
 	// fmt.Printf("...Id %q\n", *info.Id)
 	return info.Item.ID, nil
@@ -595,7 +595,7 @@ OUTER:
 		var info api.GetFolderContentsResponse
 		_, err = f.rpc(ctx, "getFolderContents", p, &info, nil)
 		if err != nil {
-			return false, errors.Wrap(err, "failed to list directory")
+			return false, fmt.Errorf("failed to list directory: %w", err)
 		}
 		for i := range info.Items {
 			item := &info.Items[i]
@@ -726,7 +726,7 @@ func (f *Fs) deleteObject(ctx context.Context, id string) (err error) {
 		"completedeletion": "n",
 	}, &info, nil)
 	if err != nil {
-		return errors.Wrap(err, "failed to delete file")
+		return fmt.Errorf("failed to delete file: %w", err)
 	}
 	return nil
 }
@@ -763,7 +763,7 @@ func (f *Fs) purgeCheck(ctx context.Context, dir string, check bool) error {
 	}, &info, nil)
 	f.dirCache.FlushDir(dir)
 	if err != nil {
-		return errors.Wrap(err, "failed to remove directory")
+		return fmt.Errorf("failed to remove directory: %w", err)
 	}
 	return nil
 }
@@ -825,7 +825,7 @@ func (f *Fs) Copy(ctx context.Context, src fs.Object, remote string) (fs.Object,
 	}
 	_, err = f.rpc(ctx, "doCopyFile", p, &info, nil)
 	if err != nil {
-		return nil, errors.Wrap(err, "failed to copy file")
+		return nil, fmt.Errorf("failed to copy file: %w", err)
 	}
 	err = dstObj.setMetaData(&info.Item)
 	if err != nil {
@@ -857,7 +857,7 @@ func (f *Fs) waitForBackgroundTask(ctx context.Context, taskID api.String) (err
 			"taskid": taskID,
 		}, &info, nil)
 		if err != nil {
-			return errors.Wrapf(err, "failed to wait for task %s to complete", taskID)
+			return fmt.Errorf("failed to wait for task %s to complete: %w", taskID, err)
 		}
 		if len(info.Tasks) == 0 {
 			// task has finished
@@ -890,7 +890,7 @@ func (f *Fs) renameLeaf(ctx context.Context, isDir bool, id string, newLeaf stri
 		"fi_name": newLeaf,
 	}, &info, nil)
 	if err != nil {
-		return nil, errors.Wrap(err, "failed to rename leaf")
+		return nil, fmt.Errorf("failed to rename leaf: %w", err)
 	}
 	err = f.waitForBackgroundTask(ctx, info.Status.TaskID)
 	if err != nil {
@@ -934,7 +934,7 @@ func (f *Fs) move(ctx context.Context, isDir bool, id, oldLeaf, newLeaf, oldDire
 			"dir_id": newDirectoryID,
 		}, &info, nil)
 		if err != nil {
-			return nil, errors.Wrap(err, "failed to move file to new directory")
+			return nil, fmt.Errorf("failed to move file to new directory: %w", err)
 		}
 		item = &info.Item
 		err = f.waitForBackgroundTask(ctx, info.Status.TaskID)
@@ -1037,7 +1037,7 @@ func (f *Fs) CleanUp(ctx context.Context) (err error) {
 	var info api.EmptyResponse
 	_, err = f.rpc(ctx, "emptyTrashInBackground", params{}, &info, nil)
 	if err != nil {
-		return errors.Wrap(err, "failed to empty trash")
+		return fmt.Errorf("failed to empty trash: %w", err)
 	}
 	return nil
 }
@@ -1164,7 +1164,7 @@ func (o *Object) modifyFile(ctx context.Context, keyValues [][2]string) error {
 		"data":  data.String(),
 	}, &info, nil)
 	if err != nil {
-		return errors.Wrap(err, "failed to update metadata")
+		return fmt.Errorf("failed to update metadata: %w", err)
 	}
 	return o.setMetaData(&info.Item)
 }
@@ -1247,7 +1247,7 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 	}
 	_, err = o.fs.rpc(ctx, "doInitUpload", p, &upload, nil)
 	if err != nil {
-		return errors.Wrap(err, "failed to initialize upload")
+		return fmt.Errorf("failed to initialize upload: %w", err)
 	}
 
 	// Cancel the upload if aborted or it fails
@@ -1290,13 +1290,13 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 		return o.fs.shouldRetry(ctx, resp, err, nil, try)
 	})
 	if err != nil {
-		return errors.Wrap(err, "failed to upload")
+		return fmt.Errorf("failed to upload: %w", err)
 	}
 	if uploader.Success != "y" {
-		return errors.Errorf("upload failed")
+		return fmt.Errorf("upload failed")
 	}
 	if size > 0 && uploader.FileSize != size {
-		return errors.Errorf("upload failed: size mismatch: want %d got %d", size, uploader.FileSize)
+		return fmt.Errorf("upload failed: size mismatch: want %d got %d", size, uploader.FileSize)
 	}
 
 	// Now finalize the file
@@ -1308,7 +1308,7 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 	}
 	_, err = o.fs.rpc(ctx, "doCompleteUpload", p, &finalize, nil)
 	if err != nil {
-		return errors.Wrap(err, "failed to finalize upload")
+		return fmt.Errorf("failed to finalize upload: %w", err)
 	}
 	finalized = true