Remove error package and cause functions (#5784)

cmd/bucket-handlers.go

@@ -34,7 +34,6 @@ import (
 	"github.com/minio/minio-go/pkg/policy"
 	"github.com/minio/minio-go/pkg/set"
 	"github.com/minio/minio/cmd/logger"
-	"github.com/minio/minio/pkg/errors"
 	"github.com/minio/minio/pkg/event"
 	"github.com/minio/minio/pkg/hash"
 )
@@ -45,7 +44,6 @@ func enforceBucketPolicy(ctx context.Context, bucket, action, resource, referer,
 	// Verify if bucket actually exists
 	objAPI := newObjectLayerFn()
 	if err := checkBucketExist(ctx, bucket, objAPI); err != nil {
-		err = errors.Cause(err)
 		switch err.(type) {
 		case BucketNameInvalid:
 			// Return error for invalid bucket name.
@@ -357,7 +355,7 @@ func (api objectAPIHandlers) DeleteMultipleObjectsHandler(w http.ResponseWriter,
 			deletedObjects = append(deletedObjects, object)
 			continue
 		}
-		if _, ok := errors.Cause(err).(ObjectNotFound); ok {
+		if _, ok := err.(ObjectNotFound); ok {
 			// If the object is not found it should be
 			// accounted as deleted as per S3 spec.
 			deletedObjects = append(deletedObjects, object)