fix some crashes, mostly related to network requests (#6187)

src/providers/twitch/TwitchChannel.cpp

@@ -1381,6 +1381,7 @@ void TwitchChannel::loadRecentMessages()
     recentmessages::load(
         this->getName(), weak,
         [weak](const auto &messages) {
+            assert(!isAppAboutToQuit());
             auto shared = weak.lock();
             if (!shared)
             {