output stack in errors

helper.go

@@ -12,6 +12,14 @@ import (
 	"gopkg.in/mgo.v2/bson"
 )
 
+func errorObject(err error) bson.M {
+	o := bson.M{"error": err.Error()}
+	if e, ok := err.(*mgocrud.ErrorWithStack); ok {
+		o["stack"] = e.Stack()
+	}
+	return o
+}
+
 func modelTypeOf(m interface{}) reflect.Type {
 	return reflect.TypeOf(
 		reflect.ValueOf(m).Elem().Interface(),