Fixed crash on leave chat

src/broadcast.h

@@ -72,6 +72,7 @@ public:
     ~Broadcast();
     void connect(Client *client, const std::function<void ()> &fct);
     void disconnect(Client *client);
+    void addToDisconnectList(Client *client);
     Wt::Json::Object reSetUser(std::string oldSessionId, std::string newSessionId);
     int count() const;
     std::string userNameForSessionId(std::string sessionId);
@@ -132,6 +133,7 @@ private:
     Wt::WDateTime lastTimeoutCheck_;
     std::unordered_map<std::string, MessageQueue> conversations_;
     std::unordered_map<std::string, std::set<std::string> > blockings_;
+    std::vector<Client *> toDisconnect_;
     void run();
     Wt::Json::Object logoutBroadcast();
     static size_t WriteCallback(void* contents, size_t size, size_t nmemb, std::string* output);