Useful or not, from you.
angular-cli WARNING environments/environment.prod.ts is part of the TypeScript compilation but it's unused

🐞 Bug report

Command (mark with an x)

<!-- Can you pin-point the command or commands that are effected by this bug? --> <!-- ✍️edit: -->

- [x] new
- [x] build

Is this a regression?

Yes, this error wasn't previously thrown.

Description

When building, new warnings are shown about unused files included in compilation.

🔬 Minimal Reproduction

ng new my-app cd my-app ng update @angular/core@next @angular/cli@next ng build --prod

🔥 Exception or Error

<pre><code> WARNING in /.../src/environments/environment.prod.ts is part of the TypeScript compilation but it's unused. </code></pre>

🌍 Your Environment

<pre><code> Angular CLI: 9.0.0-next.2 Node: 10.15.3 OS: linux x64 Angular: 9.0.0-next.4 ... animations, common, compiler, compiler-cli, core, forms ... language-service, platform-browser, platform-browser-dynamic ... router

Package Version

@angular-devkit/architect 0.900.0-next.2 @angular-devkit/build-angular 0.900.0-next.2 @angular-devkit/build-optimizer 0.900.0-next.2 @angular-devkit/build-webpack 0.900.0-next.2 @angular-devkit/core 9.0.0-next.2 @angular-devkit/schematics 9.0.0-next.2 @angular/cli 9.0.0-next.2 @ngtools/webpack 9.0.0-next.2 @schematics/angular 9.0.0-next.2 @schematics/update 0.900.0-next.2 rxjs 6.5.2 typescript 3.5.3 webpack 4.39.3

</code></pre>

That's a useful answer
Without any help

Same Error after updating.

src/app/app.server.module.ts is part of the TypeScript compilation but it's unused. Add only entry points to the 'files' or 'include' properties in your tsconfig.

`Angular CLI: 8.3.2 Node: 10.16.0 OS: win32 x64 Angular: 9.0.0-next.4 ... animations, common, compiler, compiler-cli, core, forms ... language-service, platform-browser, platform-browser-dynamic ... platform-server, router

Package Version

@angular-devkit/architect 0.803.2 @angular-devkit/build-angular 0.803.2 @angular-devkit/build-optimizer 0.803.2 @angular-devkit/build-webpack 0.803.2 @angular-devkit/core 7.3.9 @angular-devkit/schematics 7.3.9 @angular/cli 8.3.2 @angular/http 7.2.15 @ngtools/webpack 8.3.2 @nguniversal/common 7.1.1 @nguniversal/express-engine 7.1.1 @nguniversal/module-map-ngfactory-loader 7.1.1 @schematics/angular 7.3.9 @schematics/update 0.803.2 rxjs 6.5.2 typescript 3.6.2 webpack 4.39.2`