message: BaseEventIndexManager: Fix some type annotations.
diff: @@ -159,8 +159,8 @@ export default class BaseEventIndexManager {
  */
  async addHistoricEvents(
  events: [HistoricEvent],
  - checkpoint: CrawlerCheckpoint | null = null,
  - oldCheckpoint: CrawlerCheckpoint | null = null,
  + checkpoint: CrawlerCheckpoint | null,
  + oldCheckpoint: CrawlerCheckpoint | null,
  ): Promise<bool> {
  throw new Error("Unimplemented");
  }
  