The served page is blank after build

[drunkwcodes]

Beginners ask for advice, I'm writing the file according to the official Vue-material example, use

npm run build
serve -s dist/

The result of the execution is a blank screen, and there is no error in the console. What's the matter?
Thanks for advice.

github: https://github.com/drunkwcodes/matty_web

Example link:
https://codesandbox.io/s/miqgjs?module=App.vue&file=/src/App.vue