message: Fix types in `show-names`
  Fixes
diff: @@ -9,13 +9,13 @@ async function init(): Promise<false | void> {
  // `a` selector needed to skip commits by non-GitHub users
  const usernameElements = select.all('.js-discussion a.author:not(.rgh-fullname):not([href*="/apps/"]):not([href*="/marketplace/"])');
  - const usernames = new Set();
  + const usernames = new Set<string>();
  const myUsername = getUsername();
  for (const el of usernameElements) {
  el.classList.add('rgh-fullname');
  const username = el.textContent;
  if (username !== myUsername && username !== 'ghost') {
  - usernames.add(el.textContent);
  + usernames.add(el.textContent!);
  }
  // Drop 'commented' label to shorten the copy
  