Nestjs Graphql permission guard union types

Question

Using Graphql with Nestjs. I can use union types for custom excepitons like this;

export const CityUnion = createUnionType({
  name: 'CityUnion',
  types: () => [City, BaseCustomException] as const,
  resolveType(value) {
    if (value.errorCode) {
      return BaseCustomException;
    }
    return City;
  },
});

For authorization, I have permissions guards like this;

 @Query(() => [Country])
  @UseGuards(PermissionGuard)
  async countries(
    @Args('name', { type: () => String, nullable: true }) name: string,
  ) {
    return await this.countryService.findAll(name);
  }

My problem is, in case of authorization errors, client gets http 200. Is it possible to use union types in Permission guard to handle authorization errors in a schema based way?