Merge tuples types

Would need to be tested, but I think this variadic JS function would work as an implementation. It’s not exactly pretty.

const combineImpl = (...results) => {
  let result;
  for (const [data, loading, error] of results) {
    if (loading) return "Loading";
    if (result === "Unknown" || result?.TAG === "Error") continue;
    if (error) result = { TAG: "Error", _0: error };
    else if (data === undefined) result = "Unknown";
    else if (result?.TAG === "Data") result._0.push(data);
    else result = { TAG: "Data", _0: [data] };
  }
  return result ?? "Unknown";
};