*: drop github.com/pkg/errors dependency

Use standard error wrapping/unwrapping instead. The conversion is mostly
straightforward, but see grpc/grpc-go#2934 for GRPC `status.FromError`, it
doesn't currently support unwrapping/errors.As(), so we're unwrapping manually
here.

connections/pool.go

@@ -3,13 +3,14 @@ package connections
 import (
 	"context"
 	"crypto/ecdsa"
+	"errors"
+	"fmt"
 	"math/rand"
 	"sync"
 	"time"
 
 	"github.com/nspcc-dev/neofs-api-go/pkg/client"
 	"github.com/nspcc-dev/neofs-api-go/pkg/token"
-	"github.com/pkg/errors"
 	"google.golang.org/grpc"
 )
 
@@ -91,7 +92,7 @@ func new(ctx context.Context, options *PoolBuilderOptions) (Pool, error) {
 			if epi, err := c.EndpointInfo(ctx); err == nil {
 				address = epi.NodeInfo().Address()
 			}
-			return nil, errors.Wrapf(err, "failed to create neofs session token for client %s", address)
+			return nil, fmt.Errorf("failed to create neofs session token for client %s: %w", address, err)
 		}
 		clientPacks[i] = &clientPack{client: c, sessionToken: st, healthy: true}
 	}

downloader/download.go

@@ -2,6 +2,8 @@ package downloader
 
 import (
 	"context"
+	"errors"
+	"fmt"
 	"io"
 	"net/http"
 	"path"
@@ -14,7 +16,6 @@ import (
 	"github.com/nspcc-dev/neofs-api-go/pkg/object"
 	"github.com/nspcc-dev/neofs-http-gate/neofs"
 	"github.com/nspcc-dev/neofs-http-gate/tokens"
-	"github.com/pkg/errors"
 	"github.com/valyala/fasthttp"
 	"go.uber.org/zap"
 	"google.golang.org/grpc/codes"
@@ -84,10 +85,14 @@ func (r *request) receiveFile(options *neofs.GetOptions) {
 			zap.Error(err),
 		)
 		var (
-			msg  = errors.Wrap(err, "could not receive object").Error()
+			msg   = fmt.Sprintf("could not receive object: %v", err)
 			code  = fasthttp.StatusBadRequest
+			cause = err
 		)
-		if st, ok := status.FromError(errors.Cause(err)); ok && st != nil {
+		for unwrap := errors.Unwrap(err); unwrap != nil; unwrap = errors.Unwrap(cause) {
+			cause = unwrap
+		}
+		if st, ok := status.FromError(cause); ok && st != nil {
 			if st.Code() == codes.NotFound {
 				code = fasthttp.StatusNotFound
 			}
@@ -144,7 +149,7 @@ func New(ctx context.Context, log *zap.Logger, plant neofs.ClientPlant) (*Downlo
 	var err error
 	d := &Downloader{log: log, plant: plant}
 	if err != nil {
-		return nil, errors.Wrap(err, "failed to get neofs client's reusable artifacts")
+		return nil, fmt.Errorf("failed to get neofs client's reusable artifacts: %w", err)
 	}
 	return d, nil
 }

go.mod

@@ -8,7 +8,6 @@ require (
 	github.com/nspcc-dev/neo-go v0.94.0 // indirect
 	github.com/nspcc-dev/neofs-api-go v1.25.0
 	github.com/nspcc-dev/neofs-crypto v0.3.0
-	github.com/pkg/errors v0.9.1
 	github.com/prometheus/client_golang v1.9.0
 	github.com/prometheus/common v0.15.0
 	github.com/spf13/pflag v1.0.5

tokens/bearer-token.go

@@ -4,9 +4,10 @@ import (
 	"bytes"
 	"context"
 	"encoding/base64"
+	"errors"
+	"fmt"
 
 	"github.com/nspcc-dev/neofs-api-go/pkg/token"
-	"github.com/pkg/errors"
 	"github.com/valyala/fasthttp"
 )
 
@@ -77,10 +78,10 @@ func fetchBearerToken(ctx *fasthttp.RequestCtx) (*token.BearerToken, error) {
 		if buf = parse(&ctx.Request.Header); buf == nil {
 			continue
 		} else if data, err := base64.StdEncoding.DecodeString(string(buf)); err != nil {
-			lastErr = errors.Wrap(err, "could not fetch marshaled from base64")
+			lastErr = fmt.Errorf("can't base64-decode bearer token: %w", err)
 			continue
 		} else if err = tkn.Unmarshal(data); err != nil {
-			lastErr = errors.Wrap(err, "could not unmarshal bearer token")
+			lastErr = fmt.Errorf("can't unmarshal bearer token: %w", err)
 			continue
 		} else if tkn == nil {
 			continue