```ts

/** A number divided by another number, safely. */
export function safeDivide(a: number, b: number): number {
  if (Number.isNaN(a) || Number.isNaN(b)) throw new Error('Both arguments must be finite numbers.');
  if (b === 0 || b === -0) throw new Error('Cannot divide by zero.');
  return a / b;
}

```