fixed issue with tests. ES6 classes requires class vars to be established in the constructor

assets/js/WakaTime.js

@@ -6,13 +6,15 @@ import devtools from './libs/devtools-detect.js';
 
 class WakaTime {
 
-    detectionIntervalInSeconds = 60; //default
+    constructor(props) {
+        this.detectionIntervalInSeconds = 60; //default
 
-    loggingType = 'domain'; //default
+        this.loggingType = 'domain'; //default
 
-    heartbeatApiUrl = 'https://wakatime.com/api/v1/users/current/heartbeats';
+        this.heartbeatApiUrl = 'https://wakatime.com/api/v1/users/current/heartbeats';
 
-    currentUserApiUrl = 'https://wakatime.com/api/v1/users/current';
+        this.currentUserApiUrl = 'https://wakatime.com/api/v1/users/current';
+    }
 
     /**
      * Checks if the user is logged in.

assets/js/components/WakaTime.react.js

@@ -6,17 +6,20 @@ import changeExtensionIcon from '../helpers/changeExtensionIcon.js';
 import WakaTimeOriginal from '../WakaTime.js';
 
 class WakaTime extends React.Component {
-    logoutUserUrl = 'https://wakatime.com/logout';
 
-    state = {
+    constructor(props) {
-        user: {
+        super(props);
-            full_name: null,
+        this.logoutUserUrl = 'https://wakatime.com/logout';
-            email: null,
+        this.state = {
-            photo: null
+            user: {
-        },
+                full_name: null,
-        loggedIn: false,
+                email: null,
-        loggingEnabled: false
+                photo: null
-    };
+            },
+            loggedIn: false,
+            loggingEnabled: false
+        }
+    }
 
     componentDidMount() {