Added more unit tests for members resource

Aurora/Services/Server/EventManager/EventManager.cs

@@ -163,7 +163,10 @@ namespace Aurora.Services.Server.EventManager
         public void CancelEventStream(string sessionIdentifierId)
         {
             _actionList.TryGetValue(sessionIdentifierId, out EventAction value);
-            value.Cancel();
+            if (value != null)
+            {
+                value.Cancel();
+            }
 
             RemoveEventHandler(sessionIdentifierId);
         }