GO-4384 Add a non panicking method shouldcomponent

app/app.go

@@ -23,10 +23,11 @@ var (
 )
 
 var (
-	log               = logger.NewNamed("app")
-	StopDeadline      = time.Minute
-	StopWarningAfter  = time.Second * 10
-	StartWarningAfter = time.Second * 10
+	log                  = logger.NewNamed("app")
+	StopDeadline         = time.Minute
+	StopWarningAfter     = time.Second * 10
+	StartWarningAfter    = time.Second * 10
+	ErrComponentNotFound = errors.New("component not found")
 )
 
 // Component is a minimal interface for a common app.Component
@@ -179,22 +180,30 @@ func (app *App) MustComponent(name string) Component {
 	return s
 }
 
-// MustComponent - generic version of app.MustComponent
-func MustComponent[i any](app *App) i {
+func GetComponent[t any](app *App) (t, error) {
 	app.mu.RLock()
 	defer app.mu.RUnlock()
+	var empty t
 	current := app
 	for current != nil {
 		for _, s := range current.components {
-			if v, ok := s.(i); ok {
+			if v, ok := s.(t); ok {
 				app.onComponent(s)
-				return v
+				return v, nil
 			}
 		}
 		current = current.parent
 	}
-	empty := new(i)
-	panic(fmt.Errorf("component with interface %T is not found", empty))
+	return empty, ErrComponentNotFound
+}
+
+// MustComponent - generic version of app.MustComponent
+func MustComponent[t any](app *App) t {
+	component, err := GetComponent[t](app)
+	if err != nil {
+		panic(fmt.Errorf("component with interface %T is not found", new(t)))
+	}
+	return component
 }
 
 // ComponentNames returns all registered names