fix: I18nContext.current() undefined when using additional interceptors

[lucas-gregoire]

Description

I discovered a bug when using disableMiddleware: true.
When relying on I18nLanguageInterceptor to initialize the I18nContext, it's not possible to use another interceptor on the same endpoint.
When doing so, the AsyncLocalStorage containing the i18n context is broken: I18nContext.current() always returns undefined.

How to reproduce

• Set disableMiddleware: true in I18nModule options.
• Define a simple interceptor such as:

@Injectable()
export class TestInterceptor implements NestInterceptor {
  intercept(_: ExecutionContext, next: CallHandler): Observable<unknown> {
    return next.handle();
  }
}

• Add it on your endpoint:

@Get()
@UseInterceptors(TestInterceptor)
helloWorld() {
  return I18nContext.current()?.lang;
}

• This endpoint will always return undefined instead of the resolved lang. When removing the interceptor it works.

Additional context

I did something similar to the nestjs-cls's interceptor implementation: https://github.com/Papooch/nestjs-cls/blob/main/packages/core/src/lib/cls-initializers/cls.interceptor.ts
I just simplified it by passing the observer directly to the subscribe method.
I added a test in i18n-disable-middleware.e2e.spec.ts to avoid regressions.

See also:

• https://stackoverflow.com/questions/67136005/how-to-use-asynclocalstorage-for-an-observable

[coveralls]

coverage: 90.869% (+0.1%) from 90.764%
when pulling 45d148d on lucas-gregoire:fix/undefined-current-context
into 0774e23 on toonvanstrijp:main.