Stow copy error shouldn't wrap nil err

errors/error.go

@@ -2,9 +2,8 @@
 package errors
 
 import (
+	"errors"
 	"fmt"
-
-	"github.com/pkg/errors"
 )
 
 // A generic error code type.
@@ -25,12 +24,12 @@ func (e *err) Code() ErrorCode {
 
 // Overrides Is to check for error code only. This enables the default package's errors.Is().
 func (e *err) Is(target error) bool {
-	t, ok := target.(*err)
-	if !ok {
+	eCode, found := GetErrorCode(target)
+	if !found {
 		return false
 	}
 
-	return e.Code() == t.Code()
+	return e.Code() == eCode
 }
 
 type errorWithCause struct {
@@ -39,7 +38,7 @@ type errorWithCause struct {
 }
 
 func (e *errorWithCause) Error() string {
-	return fmt.Sprintf("%v, caused by: %v", e.err.Error(), errors.Cause(e))
+	return fmt.Sprintf("%v, caused by: %v", e.err.Error(), e.Cause())
 }
 
 func (e *errorWithCause) Cause() error {
@@ -90,17 +89,26 @@ func IsCausedBy(e error, errCode ErrorCode) bool {
 		Cause() error
 	}
 
+	type wrapped interface {
+		Unwrap() error
+	}
+
 	for e != nil {
 		if code, found := GetErrorCode(e); found && code == errCode {
 			return true
 		}
 
 		cause, ok := e.(causer)
-		if !ok {
-			break
+		if ok {
+			e = cause.Cause()
+		} else {
+			cause, ok := e.(wrapped)
+			if !ok {
+				break
+			}
+
+			e = cause.Unwrap()
 		}
-
-		e = cause.Cause()
 	}
 
 	return false
@@ -112,7 +120,7 @@ func IsCausedByError(e, e2 error) bool {
 	}
 
 	for e != nil {
-		if e == e2 {
+		if errors.Is(e, e2) {
 			return true
 		}
 

errors/error_test.go

@@ -35,16 +35,28 @@ func TestIsCausedBy(t *testing.T) {
 	e = Wrapf("Code2", e, "msg")
 	assert.True(t, IsCausedBy(e, "Code1"))
 	assert.True(t, IsCausedBy(e, "Code2"))
+
+	e = fmt.Errorf("new err caused by: %w", e)
+	assert.True(t, IsCausedBy(e, "Code1"))
+
+	e = fmt.Errorf("not sharing code err")
+	assert.False(t, IsCausedBy(e, "Code1"))
 }
 
 func TestIsCausedByError(t *testing.T) {
 	eRoot := Errorf("Code1", "msg")
 	assert.NotNil(t, eRoot)
+
 	e1 := Wrapf("Code2", eRoot, "msg")
 	assert.True(t, IsCausedByError(e1, eRoot))
+
 	e2 := Wrapf("Code3", e1, "msg")
 	assert.True(t, IsCausedByError(e2, eRoot))
 	assert.True(t, IsCausedByError(e2, e1))
+
+	e3 := fmt.Errorf("default errors. caused by: %w", e2)
+	assert.True(t, IsCausedByError(e3, eRoot))
+	assert.True(t, IsCausedByError(e3, e1))
 }
 
 func TestErrorsIs(t *testing.T) {

storage/stow_store.go

@@ -117,8 +117,8 @@ func (s *StowStore) ReadRaw(ctx context.Context, reference DataReference) (io.Re
 		return nil, err
 	}
 
-	if sizeBytes/MiB > GetConfig().Limits.GetLimitMegabytes {
-		return nil, errors.Wrapf(ErrExceedsLimit, err, "limit exceeded")
+	if sizeMbs := sizeBytes / MiB; sizeMbs > GetConfig().Limits.GetLimitMegabytes {
+		return nil, errors.Errorf(ErrExceedsLimit, "limit exceeded. %vmb > %vmb.", sizeMbs, GetConfig().Limits.GetLimitMegabytes)
 	}
 
 	return item.Open()

storage/stow_store_test.go

@@ -9,6 +9,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/pkg/errors"
+
 	"github.com/lyft/flytestdlib/promutils"
 
 	"github.com/graymeta/stow"
@@ -131,5 +133,6 @@ func TestStowStore_ReadRaw(t *testing.T) {
 		_, err = s.ReadRaw(context.TODO(), DataReference("s3://container/path"))
 		assert.Error(t, err)
 		assert.True(t, IsExceedsLimit(err))
+		assert.NotNil(t, errors.Cause(err))
 	})
 }