fixed TeaSpeak server crash

src/log/LogUtils.cpp

@@ -34,9 +34,8 @@ namespace logger {
             lock_guard lock(loggerLock);
             if(loggers.count(group) > 0) return loggers[group];
             //Create a new logger
-            if(group > 0){
+            if(group != 0 && group != -1)
 	            logger(0)->debug("Creating new grouped logger for group {}", group);
-            }
 
 	        vector<spdlog::sink_ptr> sinks;
 	        string path;