v5: 多个并发观察者导致 macOS 上的 child_process.fork() 发生 EBADF 错误 (与 v3 相比出现回退)

When chokidar v5 watches a large project directory (depth ≥ 4, or roughly >10,000 files/dirs), any subsequent call to child_process.fork() fails with EBADF. This is a regression from v3 which used fsevents and did not exhibit this problem.