```ts
function seatBlock(label: string): (number | string)[] {
  if (!/^\d+[A-Z]$/.test(label)) {
    throw new Error('Invalid seat label');
  }

  const digits = label.match(/\d+/)[0];
  const letter = label.charAt(label.length - 1);

  return [parseInt(digits, 10), letter];
}
```