empty assets folder

I state that I have just begun to learn all that, but i’d like to know why every time I start working on a project again (for example after reboot) assets folder is empty nonsense. I’ve never added new file in project folder, everything i do is
expo init projectFolder
npm start
and i only test over App.js. When i re-open the project assets folder is empty and i get this error:

Error: Problem validating asset fields in app.json. See https://docs.expo.io/
• Field: splash.image - cannot access file at ‘./assets/splash.png’.
• Field: icon - cannot access file at ‘./assets/icon.png’.

I’m using Ubuntu 20.04. Should i try changing folder permission?