NestJS guard crashing server when canActivate is false about nestjs-telegraf HOT 3 OPEN

export abstract class SafeGuardInterceptor
  implements NestInterceptor, CanActivate
{
  abstract canActivate(
    context: ExecutionContext,
  ): boolean | Promise<boolean> | Observable<boolean>;

  async intercept(context: ExecutionContext, next: CallHandler<any>) {
    let result = false;
    const returnValue = this.canActivate(context);
    if (isObservable(returnValue)) {
      returnValue.subscribe((value) => {
        if (value) {
          return next.handle();
        } else {
          return of(undefined);
        }
      });
      return of(undefined);
    } else {
      result = await returnValue;
      if (result) {
        return next.handle();
      }
      return of(undefined);
    }
  }
}

type Class<I, Args extends any[] = any[]> = new (...args: Args) => I;

export const UseSafeGuards = (...arr: Class<SafeGuardInterceptor>[]) =>
  UseInterceptors(...arr);

@Injectable()
export class AdminGuard extends SafeGuardInterceptor {
  canActivate(
    context: ExecutionContext,
  ): boolean | Promise<boolean> | Observable<boolean> {
    const telegraf = context.getArgByIndex<TelegrafContext>(0);
    // user is a property injected by some middleware, any logic can be used
    return !!telegraf.user?.isAdmin;
  }
}

@Update()
@UseSafeGuards(AdminGuard)
export class AdminUpdate {
    // commands or other stuff here
}