fix TLuaValue handling to be less odd

include/TLuaEngine.h

@@ -59,15 +59,7 @@ namespace fs = std::filesystem;
 /**
  * std::variant means, that TLuaArgTypes may be one of the Types listed as template args
  */
-using TLuaValue = std::variant<std::string, int, JsonString, bool, std::unordered_map<std::string, std::string>, float>;
-enum TLuaType {
-    String = 0,
-    Int = 1,
-    Json = 2,
-    Bool = 3,
-    StringStringMap = 4,
-    Float = 5,
-};
+using TLuaValue = std::variant<std::monostate, std::string, int, JsonString, bool, std::unordered_map<std::string, std::string>, float>;
 
 class TLuaPlugin;