Parallel Limit

Execute async tasks in parallel with a concurrency limit and proper error handling.

Requirements:

• Implement parallelLimit that takes tasks array and concurrency limit
• Execute at most limit tasks concurrently
• Collect all results and errors
• Return object with results and errors arrays
• Continue processing even if some tasks fail

Example:

const tasks = [
  async () => 1,
  async () => { throw new Error('fail'); },
  async () => 3,
  async () => 4
];

parallelLimit(tasks, 2).then(({ results, errors }) => {
  console.log(results); // [1, 3, 4]
  console.log(errors.length); // 1
});