```ts
/** Returns a divided by b, throws Error if divisor is zero or arguments are not finite numbers. */
export function safeDivide(a: number, b: number): number {
  if (!Number.isFinite(a) || !Number.isFinite(b)) throw new Error('Both arguments must be finite numbers.');
  if (b === 0 || b === -0) throw new Error('Divisor cannot be zero.');
  return a / b;
}
```