fix: handle missing service and route names detecting duplicates (#945)

As both Service and Route names are allowed to be empty, we have to account for 
this case in the code detecting duplicates and short-circuit when the target
entity has no name to prevent panics.

tests/integration/sync_test.go

@@ -3414,3 +3414,47 @@ func Test_Sync_UpdateWithExplicitIDs(t *testing.T) {
 		},
 	}, ignoreFieldsIrrelevantForIDsTests)
 }
+
+// test scope:
+//   - 3.0.0+
+//   - konnect
+func Test_Sync_UpdateWithExplicitIDsWithNoNames(t *testing.T) {
+	runWhenKongOrKonnect(t, ">=3.0.0")
+
+	client, err := getTestClient()
+	if err != nil {
+		t.Errorf(err.Error())
+	}
+
+	const (
+		beforeConfig = "testdata/sync/022-update-with-explicit-ids-with-no-names/before.yaml"
+		afterConfig  = "testdata/sync/022-update-with-explicit-ids-with-no-names/after.yaml"
+	)
+
+	// First, create entities with IDs assigned explicitly.
+	err = sync(beforeConfig)
+	require.NoError(t, err)
+
+	// Then, sync again, adding tags to every entity just to trigger an update.
+	err = sync(afterConfig)
+	require.NoError(t, err)
+
+	// Finally, verify that the update was successful.
+	testKongState(t, client, false, utils.KongRawState{
+		Services: []*kong.Service{
+			{
+				ID:   kong.String("c75a775b-3a32-4b73-8e05-f68169c23941"),
+				Tags: kong.StringSlice("after"),
+			},
+		},
+		Routes: []*kong.Route{
+			{
+				ID:   kong.String("97b6a97e-f3f7-4c47-857a-7464cb9e202b"),
+				Tags: kong.StringSlice("after"),
+				Service: &kong.Service{
+					ID: kong.String("c75a775b-3a32-4b73-8e05-f68169c23941"),
+				},
+			},
+		},
+	}, ignoreFieldsIrrelevantForIDsTests)
+}

tests/integration/testdata/sync/022-update-with-explicit-ids-with-no-names/after.yaml

@@ -0,0 +1,12 @@
+_format_version: "3.0"
+services:
+  - enabled: true
+    host: mockbin.org
+    id: c75a775b-3a32-4b73-8e05-f68169c23941     # Leaving ID
+    port: 80
+    tags: [after]
+    routes:
+      - id: 97b6a97e-f3f7-4c47-857a-7464cb9e202b # Leaving ID
+        paths:
+          - /r1
+        tags: [after]

tests/integration/testdata/sync/022-update-with-explicit-ids-with-no-names/before.yaml

@@ -0,0 +1,10 @@
+_format_version: "3.0"
+services:
+  - enabled: true
+    host: mockbin.org
+    id: c75a775b-3a32-4b73-8e05-f68169c23941     # Leaving ID
+    port: 80
+    routes:
+      - id: 97b6a97e-f3f7-4c47-857a-7464cb9e202b # Leaving ID
+        paths:
+          - /r1

types/route.go

@@ -188,6 +188,11 @@ func (d *routeDiffer) DuplicatesDeletes() ([]crud.Event, error) {
 }
 
 func (d *routeDiffer) deleteDuplicateRoute(targetRoute *state.Route) (*crud.Event, error) {
+	if targetRoute == nil || targetRoute.Name == nil {
+		// Nothing to do, cannot be a duplicate with no name.
+		return nil, nil
+	}
+
 	currentRoute, err := d.currentState.Routes.Get(*targetRoute.Name)
 	if errors.Is(err, state.ErrNotFound) {
 		return nil, nil

types/service.go

@@ -177,6 +177,11 @@ func (d *serviceDiffer) DuplicatesDeletes() ([]crud.Event, error) {
 }
 
 func (d *serviceDiffer) deleteDuplicateService(targetService *state.Service) ([]crud.Event, error) {
+	if targetService == nil || targetService.Name == nil {
+		// Nothing to do, cannot be a duplicate with no name.
+		return nil, nil
+	}
+
 	currentService, err := d.currentState.Services.Get(*targetService.Name)
 	if errors.Is(err, state.ErrNotFound) {
 		return nil, nil