POS Screen showing blank if I insert CSS or Js to hook

When I insert code ( * ) to hook.py (/home/frappe/frappe-bench/apps/erpnext/erpnext/hook.py)
( * ) :
app_include_js = “assets/erpnext/js/sample.js”

app_include_css = “assets/css/sample.css”

P/s: sample.js and sample.css is empty.
Is It bug?

Remove your app_include_js and app_include_css first.
Do bench build and check. May be it’s because of your custom files.

Dear @Sangram, I have tried but still not working.

I have a question: Except insert code to hook.py, where else can I insert code in the desk?

Thanks Sangram so much!

@nguyenrom you can try with this article, it has explained well about adding your custom CSS and JS.