Fixed a bug in the config.cpp

src/api/config.cpp

@@ -20,7 +20,7 @@ bool config::is_valid_config(const json& config) {
     }
 
     if (!config["database"].contains("username")) {
-        std::cout << "Config file is missing \"database.user\" field." << std::endl;
+        std::cout << "Config file is missing \"database.username\" field." << std::endl;
         return false;
     }