SwiftUI MVVM architecture - fetching cached data with refreshing

FetchCachedDataAndRefresh.swift

 public func fetchWordsetCategories() -> AnyPublisher<[WordsetCategory], Error> {
    
    let cachedDataPublisher = dao.fetchCategories()
    let refreshedDataPublisher = service.getCategories(from: "pl", to: "en")
          .flatMap { [weak self] categories in
               self?.dao.update(categories)
           }
           .eraseToAnyPublisher()
      
      return Publishers.MergeMany(cachedDataPublisher, refreshedDataPublisher)
                       .eraseToAnyPublisher()
}