optional-fields.ts:12:38 - error SC1090: JSON.stringify of 'string | undefined' values (Node's stringify of bare undefined is not a string at all — narrow with '!== undefined' first, model absence with a null arm, or use an optional record field ('{ a?: string }'), which drops from the output like Node's) are not supported yet

  11 | }
  12 | const stringifyBare = JSON.stringify(mkMaybe());
     |                                      ^~~~~~~~~
  13 | 