fix: Auto-scroll crashes when target unmounts mid-scroll — re-check mounted after await

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## 5.1.1 [#unreleased]
 
 - Fixed [#659](https://github.com/SimformSolutionsPvtLtd/showcaseview/issues/659) - Fix null-check crash in `ShowcaseController._initRootWidget` when the `Showcase` is unmounted in the same frame it mounts. Fixed by @[apurva-simform](https://github.com/apurva-simform)
+- Fixed [#662](https://github.com/SimformSolutionsPvtLtd/showcaseview/issues/662) - Fix crash and stuck scroll-loading overlay when an auto-scroll target is unmounted while the scroll animation is running. Fixed by @[fellmonkey](https://github.com/fellmonkey)
 
 ## 5.1.0
 

lib/src/showcase/showcase_controller.dart

@@ -181,13 +181,43 @@ class ShowcaseController {
       duration: showcaseView.scrollDuration,
       alignment: config.scrollAlignment,
     );
+    // The target may have been unmounted while we were waiting for the
+    // animation to finish (e.g. the page rebuilt after async data arrived).
+    if (!_mounted) {
+      isScrollRunning = false;
+      _recoverFromLostTarget();
+      return;
+    }
     // For the cases when scrollAlignment causes overscroll.
     await _waitForScrollToSettle();
+    if (!_mounted) {
+      isScrollRunning = false;
+      _recoverFromLostTarget();
+      return;
+    }
 
     isScrollRunning = false;
     setupShowcase(shouldUpdateOverlay: shouldUpdateOverlay);
   }
 
+  /// Recovers the sequence when the target is unmounted mid auto-scroll.
+  ///
+  /// The overlay is still showing [Showcase.scrollLoadingWidget] and cannot be
+  /// rebuilt from here without a context, so control is handed back to
+  /// [ShowcaseView]: skip ahead when [ShowcaseView.skipIfTargetNotPresent] is
+  /// set, otherwise end the showcase instead of leaving the barrier stuck.
+  void _recoverFromLostTarget() {
+    // [ShowcaseView._onStart] is still awaiting scrollIntoView, so defer until
+    // after the frame rather than re-entering the sequence mid-await.
+    _runLater(() {
+      if (showcaseView.skipIfTargetNotPresent) {
+        showcaseView.next(force: true);
+      } else {
+        showcaseView.dismiss();
+      }
+    });
+  }
+
   /// Handles tap on barrier area.
   ///
   /// Respects [Showcase.disableBarrierInteraction] and [ShowcaseView
@@ -468,6 +498,7 @@ class ShowcaseController {
     Duration checkInterval = const Duration(milliseconds: 60),
     int maxChecks = 120,
   }) async {
+    if (!_mounted) return;
     final scrollableState = Scrollable.maybeOf(_context);
     if (scrollableState == null) return;