add func is empty log

src/event/event_manager.hpp

@@ -14,6 +14,12 @@ namespace VE
   {
     void emit(event e)
     {
+      if (m_funcs.size() == 0) 
+      {
+        hack::warn()("funs is empty");
+        return;
+      }
+
       std::size_t i = 0;
       try
       {