Seal ReducerHook, StateHook, and Ref

CHANGELOG.md

@@ -22,8 +22,7 @@
     - markChildrenValidated
 
 #### Other API breakages
-- ReducerHook and StateHook have no public constructors and can no longer be extended
-- Ref.fromJs is now a factory constructor, meaning the Ref class can no longer be extended
+- `ReducerHook`, `StateHook`, and `Ref` are now `@sealed` and may not be inherited from
 - ReactComponentFactoryProxy.call and .build return type changed from dynamic to ReactElement
     - This matches the type returned from `build` for all subclasses, which is what’s returned by call, and reflects the type returned at runtime
     - Has potential to cause some static analysis issues, but for the most part should not affect anything since ReactElement is typically treated as an opaque type

lib/hooks.dart

@@ -2,6 +2,7 @@
 library hooks;
 
 import 'package:js/js.dart';
+import 'package:meta/meta.dart';
 import 'package:react/react.dart';
 import 'package:react/react_client/react_interop.dart';
 
@@ -16,6 +17,7 @@ import 'package:react/react_client/react_interop.dart';
 /// > * Only call Hooks from inside a [DartFunctionComponent].
 ///
 /// Learn more: <https://reactjs.org/docs/hooks-state.html>.
+@sealed
 class StateHook<T> {
   /// The first item of the pair returned by [React.useState].
   final T _value;
@@ -156,6 +158,7 @@ void useEffect(dynamic Function() sideEffect, [List<Object?>? dependencies]) {
 /// > * Only call Hooks from inside a [DartFunctionComponent].
 ///
 /// Learn more: <https://reactjs.org/docs/hooks-reference.html#usereducer>.
+@sealed
 class ReducerHook<TState, TAction, TInit> {
   /// The first item of the pair returned by [React.useReducer].
   final TState _state;

lib/react_client/react_interop.dart

@@ -92,6 +92,7 @@ Ref<T?> createRef<T>() => Ref<T?>.fromJs(React.createRef());
 /// will be available via [current].
 ///
 /// See [createRef] for usage examples and more info.
+@sealed
 class Ref<T> {
   /// A JavaScript ref object returned by [React.createRef].
   final JsRef jsRef;