src/language-css/parser-postcss.js/addMissingType
function addMissingType(node) {
  if (node && typeof node === "object") {
    delete node.parent;
    for (const key in node) {
      addMissingType(node[key]);
    }
    if (!Array.isArray(node) && node.value && !node.type) {
      node.type = "unknown";
    }
  }
  return node;
}