azurerm_network_watcher_flow_log - add nil check for traffic_analytics (#28416)

Author: neil-yechenwei

internal/services/network/network_watcher_flow_log_resource.go

@@ -559,6 +559,10 @@ func flattenNetworkWatcherFlowLogTrafficAnalytics(input *flowlogs.TrafficAnalyti
 func expandNetworkWatcherFlowLogTrafficAnalytics(d *pluginsdk.ResourceData) *flowlogs.TrafficAnalyticsProperties {
 	vs := d.Get("traffic_analytics").([]interface{})
 
+	if len(vs) == 0 {
+		return nil
+	}
+
 	v := vs[0].(map[string]interface{})
 	enabled := v["enabled"].(bool)
 	workspaceID := v["workspace_id"].(string)

internal/services/network/network_watcher_flow_log_resource_test.go

@@ -218,6 +218,13 @@ func testAccNetworkWatcherFlowLog_trafficAnalytics(t *testing.T) {
 				check.That(data.ResourceName).ExistsInAzure(r),
 			),
 		},
+		{
+			Config: r.basicConfig(data),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep(),
 	})
 }