Compiler crasher

Persistence.swift

import Foundation
import Combine

private let docsDirURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!


@propertyWrapper
struct Persisted<Value: Codable> {
  let fileName: String
  let defaultValue: Value
  
  private let encoder = JSONEncoder()
  private let decoder = JSONDecoder()
  
  private var inMemoryValue: Value?
  
  init(fileName: String, defaultValue: Value) {
    self.fileName = fileName
    self.defaultValue = defaultValue
  }
  
  private var storageURL: URL {
    return docsDirURL.appendingPathComponent(fileName)
  }
  
  var wrappedValue: Value {
    mutating get {
      if let v = inMemoryValue {
        return v
      }
      
      let v = read(from: storageURL) ?? defaultValue
      inMemoryValue = v
      return v
    }
    set {
      inMemoryValue = newValue
      write(newValue, to: storageURL)
    }
  }
  
  private func read(from url: URL) -> Value? {
    let data = try! Data(contentsOf: url)
    let decoded = try? decoder.decode(Value.self, from: data)
    return decoded
  }
  
  private func write(_ value: Value, to url: URL) {
    let data = try! encoder.encode(value)
    try! data.write(to: url)
  }
}

class PersistenceStore {
  @Persisted(fileName: "strings", defaultValue: [])
  private var _strings: [String]

  @Published private(set) var strings: [String]
}