Unable to bootstrap Nest application. "TypeError: Object prototype may only be an Object or null: undefined"

Recently I wrote for myself a demo-app based on this Ahamed Foysal's example (https://www.codementor.io/foysalit/rest-api-with-mongodb-and-nest-js-hto6x5120). As you know NestJS is a very young framework and there are catastrophicaly small number of tutorials & demo-apps for learn it. So, I create all files in the project, run mongod in separate terminal window, and run app: npm run start But the app is crashed with:

Error output

P.S. I checked - circular references in my codebase don't exists (Vue + typescript - TypeError: Object prototype may only be an Object or null: undefined).

Any help would be greatly appreciated.

In database.module.ts do a

@Module({
    components: [...databaseProviders],
    exports: [...databaseProviders],
})
export class DatabaseModule {}

three dots are required

Then in posts.module.ts

@Module({
    imports: [DatabaseModule],
    controllers: [PostsController],
    components: [PostsService, ...postsProviders],
})
export class PostsModule {}

again three dots are required

in posts.providers.ts replace DB_CONNECTION with DB_PROVIDER

Why three dots ? If you will look in posts.providers.ts it exports an array, and you want your module to import each provider separately, not the array.