Fix crash when adding recent messages to empty Channel (#3932)

* Fix crash when adding recent messages to empty Channel

* Update CHANGELOG.md

CHANGELOG.md

@@ -26,7 +26,7 @@
 - Minor: Removed total views from the usercard, as Twitch no longer updates the number. (#3792)
 - Minor: Add Quick Switcher item to open a channel in a new popup window. (#3828)
 - Minor: Warn when parsing an environment variable fails. (#3904)
-- Minor: Load missing messages from Recent Messages API upon reconnecting (#3878)
+- Minor: Load missing messages from Recent Messages API upon reconnecting (#3878, #3932)
 - Bugfix: Fix crash that can occur when closing and quickly reopening a split, then running a command. (#3852)
 - Bugfix: Connection to Twitch PubSub now recovers more reliably. (#3643, #3716)
 - Bugfix: Fix crash that can occur when changing channels. (#3799)

src/common/Channel.cpp

@@ -237,7 +237,20 @@ void Channel::addMessagesAtStart(const std::vector<MessagePtr> &_messages)
 
 void Channel::fillInMissingMessages(const std::vector<MessagePtr> &messages)
 {
+    if (messages.empty())
+    {
+        return;
+    }
+
     auto snapshot = this->getMessageSnapshot();
+    if (snapshot.size() == 0)
+    {
+        // There are no messages in this channel yet so we can just insert them
+        // at the front in order
+        this->messages_.pushFront(messages);
+        this->filledInMessages.invoke(messages);
+        return;
+    }
 
     std::unordered_set<QString> existingMessageIds;
     existingMessageIds.reserve(snapshot.size());