fix(api): ignore nil route groups

Co-Authored-By: Virgil <virgil@lethean.io>

api.go

@@ -9,6 +9,7 @@ import (
 	"errors"
 	"iter"
 	"net/http"
+	"reflect"
 	"slices"
 	"time"
 
@@ -78,6 +79,9 @@ func (e *Engine) GroupsIter() iter.Seq[RouteGroup] {
 
 // Register adds a route group to the engine.
 func (e *Engine) Register(group RouteGroup) {
+	if isNilRouteGroup(group) {
+		return
+	}
 	e.groups = append(e.groups, group)
 }
 
@@ -174,6 +178,9 @@ func (e *Engine) build() *gin.Engine {
 
 	// Mount each registered group at its base path.
 	for _, g := range e.groups {
+		if isNilRouteGroup(g) {
+			continue
+		}
 		rg := r.Group(g.BasePath())
 		g.RegisterRoutes(rg)
 	}
@@ -225,3 +232,17 @@ func (e *Engine) build() *gin.Engine {
 
 	return r
 }
+
+func isNilRouteGroup(group RouteGroup) bool {
+	if group == nil {
+		return true
+	}
+
+	value := reflect.ValueOf(group)
+	switch value.Kind() {
+	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Pointer, reflect.Slice:
+		return value.IsNil()
+	default:
+		return false
+	}
+}

modernization_test.go

@@ -94,6 +94,24 @@ func TestEngine_ChannelsIter_Good_SnapshotsCurrentChannels(t *testing.T) {
 	}
 }
 
+func TestEngine_Register_Good_IgnoresNilGroups(t *testing.T) {
+	e, _ := api.New()
+
+	var nilGroup *healthGroup
+	e.Register(nilGroup)
+
+	g1 := &healthGroup{}
+	e.Register(g1)
+
+	groups := e.Groups()
+	if len(groups) != 1 {
+		t.Fatalf("expected 1 registered group, got %d", len(groups))
+	}
+	if groups[0].Name() != "health-extra" {
+		t.Fatalf("expected the original group to be preserved, got %q", groups[0].Name())
+	}
+}
+
 func TestToolBridge_Iterators(t *testing.T) {
 	b := api.NewToolBridge("/tools")
 	desc := api.ToolDescriptor{Name: "test", Group: "g1"}