ORA-40472: invalid escape in JSON data

create or replace function tq84_o(j clob) return number as
   jsn json_object_t;
begin
   jsn := json_object_t.parse(j);
  
   return jsn.get_number('num');
end tq84_o;
/
 
 
begin
  dbms_output.put_line(tq84_o('
     {
       "num": 42,
       "txt": "hello\world"   -- Note the backslash
     }
  '));
end;
/