message: docs: Add documentation about the CLI failing
  The CLI seems to throw very non-descriptive errors. Adding a section to help users troubleshoot lazy-loading modules.
  PR Close
diff: @@ -322,6 +322,13 @@ ngOnInit() {
  For more information with a working example, see the [routing tutorial section on preloading](guide/router-tutorial-toh#preloading-background-loading-of-feature-areas).
  +## Troubleshooting lazy-loading modules
  +
  +A common error when lazy-loading modules is importing common modules in multiple places within an application. You can test for this condition by first generating the module using the Angular CLI and including the `--route route-name` parameter, where `route-name` is the name of your module. Next, generate the module without the `--route` parameter. If the Angular CLI generates an error when you use the `--route` parameter, but runs correctly without it, you may have imported the same module in multiple places.
  +
  +Remember, many common Angular modules should be imported at the base of your application.
  +
  +For more information on Angular Modules, see [NgModules](guide/ngmodules).
  ## More on NgModules and routing
  