Address code review feedback: error handling, batching, and type safety

[Copilot]

Addressed remaining code review feedback on the redis v4+ migration PR to improve error handling, performance, and type safety.

Changes

• Error message formatting: Fixed error handler to pass error object directly instead of using invalid ? placeholder

  // Before: self._server.error('Failed to initialize Redis engine: ?', error);
  // After:  self._server.error('Failed to initialize Redis engine:', error);

• Batch processing for notifications: Added batching (100 clients per batch) to prevent overwhelming Redis when publishing to channels with thousands of subscribers

  var batchSize = 100;
  for (var j = 0; j < clients.length; j += batchSize) {
    var batch = clients.slice(j, j + batchSize);
    await Promise.all(batch.map(notifyClient));
  }

• Type safety for zScore: Added defensive parsing and NaN checks since Redis clients may return strings or numbers

  var score = await this._redis.zScore(this._ns + '/clients', clientId);
  if (score !== null) {
    score = parseFloat(score);
  }
  var exists = score !== null && !isNaN(score) && /* timestamp check */;

• Documentation: Enhanced subscribe method comments to clarify memory leak risk if called multiple times on same topic

Security

CodeQL scan: 0 alerts

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