Fixes the issue with not able to send feedback after JitsiConference.leave

modules/statistics/CallStats.js

 
     CallStats.initializeFailed = false;
     CallStats.initialized = true;
+    CallStats.feedbackEnabled = true;
 
     // notify callstats about failures if there were any
     if (CallStats.reportsQueue.length) {
  */
 var CallStats = _try_catch(function(jingleSession, Settings, options) {
     try{
-        //check weather that should work with more than 1 peerconnection
-        if(!callStats) {
-            callStats = new callstats($, io, jsSHA);
-        } else {
-            return;
-        }
+        CallStats.feedbackEnabled = false;
+        callStats = new callstats($, io, jsSHA);
 
         this.session = jingleSession;
         this.peerconnection = jingleSession.peerconnection.peerconnection;
  */
 CallStats.initializeFailed = false;
 
+/**
+ * Shows weather sending feedback is enabled or not
+ * @type {boolean}
+ */
+CallStats.feedbackEnabled = false;
+
 /**
  * Checks whether we need to re-initialize callstats and starts the process.
  * @private
  */
 CallStats.prototype.sendFeedback = _try_catch(
 function(overallFeedback, detailedFeedback) {
-    if(!CallStats.initialized) {
+    if(!CallStats.feedbackEnabled) {
         return;
     }
     var feedbackString =    '{"userID":"' + this.userID + '"' +
  * Clears allocated resources.
  */
 CallStats.dispose = function () {
-    callStats = null;
+    // The next line is commented because we need to be able to send feedback
+    // even after the conference has been destroyed.
+    // callStats = null;
     CallStats.initialized = false;
     CallStats.initializeFailed = false;
     CallStats.initializeInProgress = false;

modules/statistics/statistics.js

 Statistics.prototype.stopCallStats = function () {
     if(this.callstats) {
         var index = Statistics.callsStatsInstances.indexOf(this.callstats);
-        Statistics.callsStatsInstances.splice(index, 1);
-        this.callstats = null;
+        if(index > -1)
+            Statistics.callsStatsInstances.splice(index, 1);
+        // The next line is commented because we need to be able to send
+        // feedback even after the conference has been destroyed.
+        // this.callstats = null;
         CallStats.dispose();
     }
 };