@State var newType = "" causes the view to fail, removing it fixes the issue and I have no idea why.

import SwiftUI
import CoreData

struct AddTaskView: View {

    @Environment(\.managedObjectContext) private var viewContext
    @Environment(\.presentationMode) var presentationMode

    @FetchRequest(entity: Task.entity(), sortDescriptors: [])
    var tasks: FetchedResults<Task>

    @FetchRequest(entity: DailyScore.entity(), sortDescriptors: [NSSortDescriptor(key: "date", ascending: false)])
    var scores: FetchedResults<DailyScore>

    let types = ["Exercise", "German", "Cold Shower", "Fast Food"]

    @State var selectedTaskIndex = 0
    @State var newType = ""

    var body: some View {

Here is the full code if interested: https://pastebin.com/dHfMi6sU Also, it only crashes the preview, not the simulator.

Works fine for me in Xcode 12.5.1