fix defaults on create-slug

Author: appinteractive

server/hooks/create-slug.js

@@ -3,8 +3,10 @@ const slug = require('slug');
 const getUniqueSlug = require('../helper/get-unique-slug');
 const { isEmpty } = require('lodash');
 
-module.exports = function (options = { field: null, overwrite: false, unique: true }) {
+module.exports = function (options = {}) {
   return function (hook) {
+    options = Object.assign({ field: null, overwrite: false, unique: true }, options);
+
     if (!options.field || !hook.data[options.field]) return hook;
 
     // do not overwrite existing slug