Avoid analytics exception when disabled (#684)

* log: Logs when analytics are disposed, drops events early.

* fix: Adds a missing parameter to a function call.

JitsiMeetJS.js

         }
 
         if (options.enableAnalyticsLogging !== true) {
+            logger.warn('Analytics disabled, disposing.');
             this.analytics.dispose();
         }
 

modules/RTC/ScreenObtainer.js

                     if (firefoxExtInstalled === null) {
                         firefoxExtInstalled = false;
                     }
-                    this.obtainScreenOnFirefox(callback, errorCallback);
+                    this.obtainScreenOnFirefox(
+                        options, callback, errorCallback);
                 },
                 300);
             logger.log(

modules/statistics/AnalyticsAdapter.js

      * Dispose analytics. Clears all handlers.
      */
     dispose() {
+        logger.warn('Disposing of analytics adapter.');
         this.setAnalyticsHandlers([]);
         this.disposed = true;
     }
      * event, if eventName is a string.
      */
     sendEvent(eventName, properties = {}) {
+        if (this.disposed) {
+            logger.warn('Not sending an event, disposed.');
+
+            return;
+        }
+
         let event = null;
 
         if (typeof eventName === 'string') {