message: Fix errors in `open-all-notifications`
diff: @@ -70,7 +70,11 @@ function addOpenAllButton(): void {
  // Create an open button and add it into a button group
  const button = <button className="btn btn-sm rgh-open-notifications-button">Open all unread in tabs</button>;
  select('.tabnav .float-right')!.prepend(button);
  - groupButtons([button, button.nextElementSibling!]);
  +
  + // There is no sibling on `/<org>/<repo>/notifications` page
  + if (button.nextElementSibling) {
  + groupButtons([button, button.nextElementSibling]);
  + }
  }
  }
  