Angular 9: Value at position X in the NgModule.imports is not a reference

Question

I upgraded an Angular App from v8 to v9. The project imports a custom UI library using Angular 8 and moment.js.

When I build it:

1. It generates a warning:

WARNING in Entry point '@myLib/catalogue' contains deep imports into
 '/Users/xyz/Projects/forms-frontend/node_modules/moment/locale/de'.
This is probably not a problem, but may cause the compilation of entry points to be out of order.

In the @myLib/catalogue.js file of the library (inside node_modules folder), the moment.js DE locale is imported as following:

import 'moment/locale/de';

2. Compilation errors are also triggered:

ERROR in Failed to compile entry-point @myLib/catalogue (es2015 as esm2015) due to compilation errors:
node_modules/@myLib/catalogue/fesm2015/catalogue.js:213:26 - error NG1010: Value at position 2 in the NgModule.imports of FormInputModule is not a reference: [object Object]

213                 imports: [
                             ~
214                     CommonModule,
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
... 
219                     TranslateModule
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
220                 ],
    ~~~~~~~~~~~~~~~~~

The text of the warning seems explaining exactly the compilation error, where the position (2 in this case) is out of range of the imports array.

I have seen different articles/github issues about deep-links, but no working solution.

Answer 1

you might have used npm i and the editor might fail to generate the build correctly. Try restarting your editor. Restarting worked for me. I was using VSCode

Answer 2

you need to change your custom build of modules, so you need to make analog changes to the ones below, in my case i needed to change:

export class ThemeModule {
  static forRoot(): ModuleWithProviders {
    return <ModuleWithProviders>{
      ngModule: ThemeModule,
      providers: [
        ...NbThemeModule.forRoot(
          {
            name: 'default',
          },
          [DEFAULT_THEME, COSMIC_THEME, CORPORATE_THEME, DARK_THEME],
        ).providers,
      ],
    };
  }
}

to:

export class ThemeModule {
  static forRoot(): ModuleWithProviders<ThemeModule> {
    return {
      ngModule: ThemeModule,
      providers: [
        ...NbThemeModule.forRoot(
          {
            name: 'default',
          },
          [DEFAULT_THEME, COSMIC_THEME, CORPORATE_THEME, DARK_THEME],
        ).providers,
      ],
    };
  }
}