Fix parser_yaml.hpp to parse null lines

include/core/yaml/parser_yaml.hpp

@@ -355,6 +355,8 @@ void ParserYAML::walkTreeR(YAML::Node n, std::vector<std::string>& tags, std::st
       }
         break;
     }
+      case YAML::NodeType::Null :
+        break;
     default:
         assert(1 == 0 && "Unsupported node Type at walkTreeR.");
         break;