message: prevent user from importing `ref`
diff: @@ -47,7 +47,9 @@ export default function Step1Columns({ config, setConfig }: IStepProps) {
  const sample = tableState!.rows.slice(0, 50);
  const fields_ = new Set<string>();
  sample.forEach((doc) =>
  - Object.keys(doc).forEach((key) => fields_.add(key))
  + Object.keys(doc).forEach((key) => {
  + if (key !== "ref") fields_.add(key);
  + })
  );
  return Array.from(fields_).sort();
  }, [tableState?.rows]);
  