执行npm start后报错：
Error watching file for changes: EMFILE
{"code":"EMFILE","errno":"EMFILE","syscall":"Error watching file for changes:","filename":null}
Error: Error watching file for changes: EMFILE
at exports._errnoException (util.js:949:11)
at FSEvent.FSWatcher._handle.onchange (fs.js:1400:11)
解决办法：重新安装watchman
1、卸载所有已安装的watchman：brew uninstall --force watchman
2、删除watchman相关文件：rm -rf /usr/local/var/run/watchman/
3、重新安装watchman：brew install watchman