```ts
export function lineNumber(block: string): string {
  if (block === "") return "";
  
  const lines = block.split("\n");
  const maxLineLength = Math.max(...lines.map(line => line.length));
  
  return lines.map((line, index) => `${index + 1}: ${line.padStart(maxLineLength, " ")}`).join("\n");
}
```