```ts
export function lineChokePoint(stations: Array<[string, number, number]>): { station: string; output: number } {
  if (stations.length === 0) {
    throw new Error("Station list cannot be empty.");
  }

  const capacityMap = new Map<string, number>();
  let chokePoint = "";
  let minCapacity = Infinity;

  for (const [name, machines, rate] of stations) {
    if (typeof name !== "string" || name.trim() === "") {
      throw new Error("Station name must be a non-empty string.");
    }
    if (!Number.isInteger(machines) || machines <= 0) {
      throw new Error("Machine count must be a positive integer.");
    }
    if (!Number.isInteger(rate) || rate <= 0) {
      throw new Error("Rate per machine must be a positive integer.");
    }

    const capacity = machines * rate;
    if (capacityMap.has(name)) {
      throw new Error(`Station name "${name}" appears twice.`);
    }

    capacityMap.set(name, capacity);

    if (capacity < minCapacity) {
      minCapacity = capacity;
      chokePoint = name;
    }
  }

  return { station: chokePoint, output: minCapacity };
}
```