```ts
export function paceOf(seconds: number, kilometres: number): number {
  if (kilometres === 0) {
    throw new Error("Cannot calculate pace for a leg with zero distance.");
  }
  return Math.floor((seconds / kilometres) * 3600);
}

export function paceList(legs: { seconds: number; kilometres: number }[]): number[] {
  return legs.filter(leg => leg.kilometres > 0).map(leg => paceOf(leg.seconds, leg.kilometres));
}
```