Update TraceUtilityNetworkView.Model.swift

Author: dfeinzimer

Shared/Samples/Trace utility network/TraceUtilityNetworkView.Model.swift

@@ -218,16 +218,17 @@ extension TraceUtilityNetworkView {
         /// - Note: Elements are grouped by network source prior to selection so that all selections
         /// per operational layer can be made at once.
         func trace() async throws {
-            guard let pendingTraceParameters = pendingTraceParameters else { return }
-            let traceResults = try await network?.trace(using: pendingTraceParameters)
-                .filter { $0 is UtilityElementTraceResult }
-            for result in traceResults as? [UtilityElementTraceResult] ?? [] {
+            guard let network, let pendingTraceParameters = pendingTraceParameters else { return }
+            let traceResults = try await network
+                .trace(using: pendingTraceParameters)
+                .compactMap { $0 as? UtilityElementTraceResult }
+            for result in traceResults {
                 let groups = Dictionary(grouping: result.elements) { $0.networkSource.name }
                 for (networkName, elements) in groups {
                     guard let layer = map.operationalLayers.first(
                         where: { ($0 as? FeatureLayer)?.featureTable?.tableName == networkName }
                     ) as? FeatureLayer else { continue }
-                    let features = try await network?.features(for: elements) ?? []
+                    let features = try await network.features(for: elements)
                     layer.selectFeatures(features)
                 }
             }