问在VStack中使用list时，获取“表达式的类型不明确”

EN

import SwiftUI
import FirebaseAuth
import FirebaseFirestore

struct MainView: View {
    
    @State private var radius = 300
    private var name = "Name"
    @ObservedObject private var viewModel = TaskViewModel()
    
    let db = Firestore.firestore()
    
    init() { UITableView.appearance().backgroundColor = .clear
        UITableView.appearance().isScrollEnabled = false
    }
    
    var body: some View {
        
        return NavigationView(content: {
            
            VStack {
                Spacer()
                    .frame(height: 150)
                
                List(viewModel.task) { item in
                    VStack(alignment: .leading) {
                        Image(systemName: item.completedIcon)
                        Text(item.title).font(Font.custom("Permanent Marker", size: 18))
                    }
                }.navigationBarTitle("Tasks")
                .onAppear() {
                    self.viewModel.fetchData()
                }
                .frame(width: 318, height: 404, alignment: .center)
                .shadow(radius: 7)
                .cornerRadius(25.0)
                .listRowBackground(Color.white)

            }
            
        })
        
    }
}