onmessage = (e) => {
  const data = JSON.stringify(e.data.editorState, getCircularReplacer(), e.data.spaces);
  postMessage(data);
};

const getCircularReplacer = () => {
  const seen = new WeakSet();
  return (key, value) => {
    if (key === 'parent') {
      return;
    }

    if (key === 'SelectedContainer') {
      return;
    }

    if (typeof value === 'object' && value !== null) {
      if (seen.has(value)) {
        return;
      }
      seen.add(value);
    }
    return value;
  };
};