black page in https://localhost:190002

Dear Sirs,

Please teach me how to fix the above issue

I have followed the tutorial https://www.youtube.com/watch?v=qSRrxpdMpVc
at 23:27 mins tried to create rn-first-app and run “npm start” at my macbook pro terminal , then the https://localhost:19002 shown black page

Thanks
Fc