fix(ui): Fix segmentation fault when opening the message log (endless…

…-sky#9675)

source/Messages.cpp

@@ -39,7 +39,7 @@ void Messages::Add(const string &message, Importance importance)
 {
 	lock_guard<mutex> lock(incomingMutex);
 	incoming.emplace_back(message, importance);
-	if(message != logged.front().first)
+	if(logged.empty() || message != logged.front().first)
 	{
 		logged.emplace_front(message, importance);
 		if(logged.size() > MAX_LOG)