stringifiable type with TS

stringifiable.ts

export type Stringifiable = object | string | boolean | number | null;

export const stdMarker = 'gfy';

export const getJSONCanonical = function (v: Stringifiable, marker?: string) {

  marker = marker || stdMarker;

  return JSON.stringify({
    [marker]: true,
    value: v
  });

};

getJSONCanonical(undefined);  // no compilation error?