Fix demo crash when deleting SwiftData discoveries on device

Route store writes through Task.detached so MainActor-inherited tasks
do not run SwiftData mutations on the main thread. Delete by fetching
in the actor's ModelContext instead of model(for:) with IDs from @query.

Author: itsniper

Demo/ReliaBLE Demo/ReliaBLE Demo/Central/CentralViewModel.swift

@@ -66,15 +66,24 @@ import ReliaBLE
     }
 
     func clearAllData() {
-        Task { await deviceStore?.clearAll() }
+        guard let deviceStore else { return }
+        Task.detached {
+            await deviceStore.clearAll()
+        }
     }
 
     func deleteDiscoveries(ids: [PersistentIdentifier]) {
-        Task { await deviceStore?.deleteDiscoveries(ids: ids) }
+        guard let deviceStore else { return }
+        Task.detached {
+            await deviceStore.deleteDiscoveries(ids: ids)
+        }
     }
 
     func deleteDevices(ids: [PersistentIdentifier]) {
-        Task { await deviceStore?.deleteDevices(ids: ids) }
+        guard let deviceStore else { return }
+        Task.detached {
+            await deviceStore.deleteDevices(ids: ids)
+        }
     }
 
     private func parseServices(from input: String) -> [CBUUID]? {

Demo/ReliaBLE Demo/ReliaBLE Demo/Central/DeviceStoreActor.swift

@@ -103,24 +103,34 @@ actor DeviceStoreActor: ModelActor {
 
     func deleteDiscoveries(ids: [PersistentIdentifier]) {
         assertWritesOffMainThread()
+        guard !ids.isEmpty else { return }
 
-        for id in ids {
-            if let event = modelContext.model(for: id) as? DiscoveryEvent {
+        let idSet = Set(ids)
+        do {
+            let events = try modelContext.fetch(FetchDescriptor<DiscoveryEvent>())
+            for event in events where idSet.contains(event.persistentModelID) {
                 modelContext.delete(event)
             }
+            try modelContext.save()
+        } catch {
+            print("Failed to delete discoveries: \(error)")
         }
-        try? modelContext.save()
     }
 
     func deleteDevices(ids: [PersistentIdentifier]) {
         assertWritesOffMainThread()
+        guard !ids.isEmpty else { return }
 
-        for id in ids {
-            if let device = modelContext.model(for: id) as? Device {
+        let idSet = Set(ids)
+        do {
+            let devices = try modelContext.fetch(FetchDescriptor<Device>())
+            for device in devices where idSet.contains(device.persistentModelID) {
                 modelContext.delete(device)
             }
+            try modelContext.save()
+        } catch {
+            print("Failed to delete devices: \(error)")
         }
-        try? modelContext.save()
     }
 
     private func assertWritesOffMainThread() {