Angular5 :polyfills.ts & \main.ts is missing from the TypeScript compilation

[Jalle]

This is my Angular5 project structure.

 

Both `tsconfig.app.json` and `package.json` contain this section 

     "include": [
          "/src/main.ts",
          "/src/polyfills.ts"
        ]

But no matter what I try I still get this error:

    \polyfills.ts & \main.ts is missing from the TypeScript compilation. Please make sure it is in your tsconfig via the 'files' or 'include' property.

Anyone has idea what's missing here?