Build/main.js in PWA has all the source code! How to protect my PWA?

Ionic 3 PWA: when I visit my pwa website (https://*****.com/pwa/build/main.js), I can see all the source code! how can I protect this file and make my PWA secure?
Please help.

I solved it.
I created “.haccess” file inside “build” directory:

RewriteEngine On
RewriteCond %{HTTP_REFERER} !^https://(.+.)? [NC]
RewriteRule .*.(js|css|map)$ - [F]