I want to resolve docsCount field for ModuleStats but I get an error Error: Undefined resolver type error. Make sure you are providing an explicit object type for the "ModuleStatsResolver"

@ObjectType()
export class ModuleStats {
  @Field(() => ID)
  _id: string;
  @Field()
  name: string;
  @Field(() => Int)
  docsCount: number;
}

@Resolver(() => ModuleStats)
export class ModuleStatsResolver {
  @Query(() => ModuleStats)
  async getModuleStats(@Args() args: ModuleArgs) {
    return await this.moduleService.getStats(args);
  }

  @ResolveField("docsCount", () => Int)
  async getDocsCount(@Parent() moduleStats: ModuleStats) {
    return await this.docsService.getCount(moduleStats._id);
  }
}