--- node_modules/service-worker-mock/fetch.js	2021-02-18 13:47:55.000000000 -0700
+++ patches/service-worker-mock-fixed.js	2021-02-18 15:49:47.000000000 -0700
@@ -1,8 +1,11 @@
 module.exports = async (request) => {
+  const Response = require('./models/Response');
   const response = new Response('Response from service-worker-mock/fetch.js', {
     status: 200,
     statusText: 'ok.'
   });
-  response.url = request.url;
+  if (request && request.url) {
+    response.url = request.url;
+  }
   return response;
 };