fix: Hide environment.prod.ts included in compilation warning

Author: shanmukhateja

demo/src/tsconfig.app.json

@@ -6,6 +6,10 @@
     "baseUrl": "",
     "types": []
   },
+  "files": [
+    "./main.ts",
+    "./polyfills.ts"
+  ],
   "exclude": [
     "test.ts",
     "**/*.spec.ts"