fix: crash if GUM not called

Fixes crash on undefined var in case get user media was not called,
before the conference started.

JitsiMeetJS.js

@@ -118,6 +118,12 @@ export default {
     init(options) {
         Statistics.init(options);
 
+        // Initialize global window.connectionTimes
+        // FIXME do not use 'window'
+        if (!window.connectionTimes) {
+            window.connectionTimes = {};
+        }
+
         this.analytics = Statistics.analytics;
         if (options.enableAnalyticsLogging === true) {
             this.analytics.init(RTCBrowserType.getBrowserName());

modules/RTC/JitsiRemoteTrack.js

@@ -214,11 +214,18 @@ export default class JitsiRemoteTrack extends JitsiTrack {
         console.log(`(TIME) Render ${type}:\t`, now);
         this.conference.getConnectionTimes()[`${type}.render`] = now;
 
+        // The conference can be started without calling GUM
+        // FIXME if there would be a module for connection times this kind
+        // of logic (gumDuration or ttfm) should end up there
+        const gumStart = window.connectionTimes['obtainPermissions.start'];
+        const gumEnd = window.connectionTimes['obtainPermissions.end'];
+        const gumDuration
+            = !isNaN(gumEnd) && !isNaN(gumStart) ? gumEnd - gumStart : 0;
+
         const ttfm = now
             - (this.conference.getConnectionTimes()['session.initiate']
             - this.conference.getConnectionTimes()['muc.joined'])
-            - (window.connectionTimes['obtainPermissions.end']
-            - window.connectionTimes['obtainPermissions.start']);
+            - gumDuration;
 
         this.conference.getConnectionTimes()[`${type}.ttfm`] = ttfm;
         console.log(`(TIME) TTFM ${type}:\t`, ttfm);