Invalid Module export

Module.exports contains a Provider token that is unregistered, unimported, or invisible to the Module.

Reproduction

Only Providers visible to the current Module can be exported:

src/app.module.ts

import { Injectable, Module, createApp } from 'func'

@Injectable()
class ProjectService {}

@Module({ exports: [ProjectService] })
class AppModule {}

createApp(AppModule)

How to fix it

If the current Module provides the token, add it to providers first. If it comes from an imported Module, make sure the source Module exports it, then import that Module before re-exporting the token. A Command class is not a Provider and cannot appear in exports.