Fix setState() called after dispose() in UncontrolledProviderScope

Adds a mounted check before calling setState() in the frame callback
scheduled by UncontrolledProviderScope.build(). This prevents the error
when ProviderScope instances are used in scrollable lists and get
disposed while frame callbacks are still pending.

Fixes #4661

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: itsatifsiddiqui

packages/flutter_riverpod/CHANGELOG.md

@@ -1,3 +1,7 @@
+## Unreleased fix
+
+- Fixed `setState() called after dispose()` error in `UncontrolledProviderScope` when used in scrollable lists (thanks to @itsatifsiddiqui)
+
 ## 3.2.1 - 2026-02-03
 
 - Fixed a bug where resuming a paused provider could cause it to never

packages/flutter_riverpod/lib/src/core/provider_scope.dart

@@ -362,7 +362,9 @@ To fix this problem, you have one of two solutions:
     /// This is for scoped providers to correctly update without causing a
     /// markNeedsBuild error.
     WidgetsBinding.instance.scheduleFrameCallback(scheduleNewFrame: false, (_) {
-      setState(() {});
+      if (mounted) {
+        setState(() {});
+      }
     });
 
     return _UncontrolledProviderScope(