fix: ensure liveupdate pubsubs exit (#5557)

Previously, the derived class (i.e. BttvLiveUpdates or SeventvEventAPI)
    would have their destructor ran before BasicPubSubManager called
    stop, meaning there was a time wherein messages could still flow
    through, attempting to call `onMessage` on a pure virtual, causing a
    crash.

src/providers/liveupdates/BasicPubSubManager.hpp

@@ -99,7 +99,8 @@ public:
 
     virtual ~BasicPubSubManager()
     {
-        this->stop();
+        // The derived class must call stop in its destructor
+        assert(this->stopping_);
     }
 
     BasicPubSubManager(const BasicPubSubManager &) = delete;
@@ -127,6 +128,11 @@ public:
 
     void stop()
     {
+        if (this->stopping_)
+        {
+            return;
+        }
+
         this->stopping_ = true;
 
         for (const auto &client : this->clients_)
@@ -138,10 +144,20 @@ public:
 
         if (this->mainThread_->joinable())
         {
-            this->mainThread_->join();
+            // NOTE: We spawn a new thread to join the websocket thread.
+            // There is a case where a new client was initiated but not added to the clients list.
+            // We just don't join the thread & let the operating system nuke the thread if joining fails
+            // within 1s.
+            auto joiner = std::async(std::launch::async, &std::thread::join,
+                                     this->mainThread_.get());
+            if (joiner.wait_for(std::chrono::seconds(1)) ==
+                std::future_status::timeout)
+            {
+                qCWarning(chatterinoLiveupdates)
+                    << "Thread didn't join within 1 second, rip it out";
+                this->websocketClient_.stop();
+            }
         }
-
-        assert(this->clients_.empty());
     }
 
 protected: