svoid assertNoException(S msg default "", Runnable r) {
  try {
    r.run();
  } catch e {
    fail(msg, e);
  }
}

svoid assertNoException(Scorer scorer, S msg default "", Runnable r) {
  try {
    r.run();
    scorer.ok(msg);
  } catch e {
    scorer.error(toPersistableThrowable(new RuntimeException(msg, e)));
  }
}