allow to set any message as error

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

options.go

@@ -2,6 +2,7 @@ package http
 
 import (
 	"context"
+	"fmt"
 	"net/http"
 
 	"github.com/unistack-org/micro/v3/server"
@@ -12,6 +13,18 @@ type rspCodeVal struct {
 	code int
 }
 
+func SetError(err interface{}) error {
+	return &Error{err: err}
+}
+
+type Error struct {
+	err interface{}
+}
+
+func (err *Error) Error() string {
+	return fmt.Sprintf("%v", err.err)
+}
+
 // SetRspCode saves response code in context, must be used by handler to specify http code
 func SetRspCode(ctx context.Context, code int) {
 	if rsp, ok := ctx.Value(rspCodeKey{}).(*rspCodeVal); ok {