SampleRepositoryReturningResult.kt

// domain
sealed class ErrorEntity {
  
    sealed class ApiError: ErrorEntity() {
        // .....
    }

    sealed class FileError: ErrorEntity() {
        
        object NotFound: FileError()
        
        object ReadError:  FileError()
    }
}

// domain
interface FileRepository {

    fun loadFile(fileName: String): Result<String>
}

// data layer
class AndroidFileRepository : FileRepository {

    override fun loadFile(fileName: String): Result<String> {
        return try {
            val fileContent = File(fileName).inputStream().readBytes().toString(Charsets.UTF_8)
            Result.Success(fileContent)
        } catch (e: FileNotFoundException) {
            Result.Error(ErrorEntity.FileError.NotFound)
        } catch (e: IOException) {
            Result.Error(ErrorEntity.FileError.ReadError)
        }
    }
}