done() never called with error

[daradermody]

In these lines:

  check(cmd, err, stdout, stderr);
  if (done) { done(err, stdout, stderr); }

The check() function calls process.exit(1) if err is truthy, which means done() never actually gets called where this has been an error, so this scenario can be handled by the code using this library. Should process.exit() be called only if there is no done function?