message: Handle Arch non/error in ArchToString
diff: @@ -57,6 +57,8 @@ Arch ParseArch(std::string arch) {
  std::string ArchToString(Arch arch) {
  switch (arch) {
  + case Arch::none:
  + return "none";
  case Arch::x86:
  return "x86";
  case Arch::x86_64:
  @@ -65,6 +67,8 @@ std::string ArchToString(Arch arch) {
  return "arm";
  case Arch::aarch64:
  return "aarch64";
  + case Arch::error:
  + return "error";
  default:
  // none and error are not supposed to be printed.
  Error(SourcePos(), "Invalid arch is processed");
  