Add note for improvement

doc/developer.md

@@ -43,6 +43,8 @@ if (reply.isEmpty())) {
 }
 ```
 
+Yes, `isEmpty()` is not a very strict check, we could actually check for valid-looking JSON (starts with a { and ends with a }) as well as making sure the keys "seed" and "birthday" exist. Please implement this.
+
 When checking the return value of `litelib_initialize_new`  it should look like :
 
 ```