```ts
export function checkManifest(line: Record<string, unknown>): Record<string, unknown> {
  const { sku, count, note } = line;

  if (typeof sku !== 'string' || !sku.trim()) {
    throw new Error('Invalid sku');
  }

  if (!Number.isInteger(count) || count <= 0) {
    throw new Error('Invalid count');
  }

  if (typeof note !== 'string') {
    throw new Error('Invalid note');
  }

  return { sku, count, note };
}
```