check src existence

lib/util.js

@@ -124,8 +124,8 @@ function generatePreviewHead(parsedConfig) {
 
   for(const key of Object.keys(parsedConfig)) {
     for(const value of parsedConfig[key]) {
-      if(key == 'script' && value.src) {
-        if(value.src.indexOf('ember-cli-live-reload.js') > -1) {
+      if(key == 'script') {
+        if(value.src && value.src.indexOf('ember-cli-live-reload.js') > -1) {
           doc.push(`<script>
             (function() {
               var srcUrl = null;
@@ -144,7 +144,7 @@ function generatePreviewHead(parsedConfig) {
           continue;
         }
         doc.push(`<${key} ${objectToHTMLAttributes(value)}></${key}>`);
-        if(value.src.match(/assets\/vendor[^.]*\.js/)) {
+        if(value.src && value.src.match(/assets\/vendor[^.]*\.js/)) {
           // make sure we push this right after vendor to ensure the application does not bind to the window.
           doc.push('<script>window.Ember = require("ember").default; runningTests = true; Ember.testing=true;</script>');
         }