Use function to define data instead of an object

app/assets/javascripts/pipelines/pipeline_details_bundle.js

@@ -11,8 +11,10 @@ document.addEventListener('DOMContentLoaded', () => {
 
   const pipelineGraphApp = new Vue({
     el: '#js-pipeline-graph-vue',
-    data: {
+    data() {
+      return {
         mediator,
+      };
     },
     components: {
       pipelineGraph,

app/assets/javascripts/pipelines/pipeline_details_mediatior.js

@@ -6,8 +6,8 @@ import PipelineStore from './stores/pipeline_store';
 import PipelineService from './services/pipeline_service';
 
 export default class pipelinesMediator {
-  constructor(options) {
-    this.options = options || {};
+  constructor(options = {}) {
+    this.options = options;
     this.store = new PipelineStore();
     this.service = new PipelineService(options.endpoint);