fix error decode (#1068)

* fix error decode

transport/http/client.go

@@ -298,6 +298,7 @@ func DefaultErrorDecoder(ctx context.Context, res *http.Response) error {
 	if err == nil {
 		e := new(errors.Error)
 		if err = CodecForResponse(res).Unmarshal(data, e); err == nil {
+			e.Code = int32(res.StatusCode)
 			return e
 		}
 	}

transport/http/client_test.go

@@ -4,12 +4,13 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
-	"github.com/go-kratos/kratos/v2/errors"
 	"io/ioutil"
 	nethttp "net/http"
 	"testing"
 	"time"
 
+	"github.com/go-kratos/kratos/v2/errors"
+
 	"github.com/stretchr/testify/assert"
 
 	"github.com/go-kratos/kratos/v2/registry"
@@ -161,7 +162,7 @@ func TestDefaultErrorDecoder(t *testing.T) {
 	}
 	err2 := DefaultErrorDecoder(context.TODO(), resp2)
 	assert.Error(t, err2)
-	assert.Equal(t, int32(54321), err2.(*errors.Error).GetCode())
+	assert.Equal(t, int32(500), err2.(*errors.Error).GetCode())
 	assert.Equal(t, "hi", err2.(*errors.Error).GetMessage())
 	assert.Equal(t, "FOO", err2.(*errors.Error).GetReason())
 }