fix(app): catch if the scroll controller does not have clients

Author: tamslo

app/lib/common/widgets/scrollable_stack_with_indicator.dart

@@ -33,10 +33,7 @@ class ScrollableStackWithIndicator extends HookWidget {
     return scrollPosition.pixels >= maxScrollOffset;
   }
 
-  double? _getRelativeScrollPosition(
-    GlobalKey contentKey,
-    ScrollPosition scrollPosition,
-  ) {
+  double? _getRelativeScrollPosition(ScrollPosition scrollPosition) {
     final maxScrollOffset = scrollPosition.maxScrollExtent;
     final relativePosition =
       1 - (maxScrollOffset - scrollPosition.pixels) / maxScrollOffset;
@@ -53,6 +50,7 @@ class ScrollableStackWithIndicator extends HookWidget {
     final scrollbarPadding = rightScrollbarPadding ?? PharMeTheme.smallSpace;
     final horizontalPadding = scrollbarPadding + 3 * scrollbarThickness;
     final contentKey =  GlobalKey();
+    final failedIndicatorInitializationAttempts = useState(0);
     final showScrollIndicatorButton = useState(false);
     final scrollIndicatorButtonOpacity = useState<double>(1);
     final scrollController = useScrollController(
@@ -61,12 +59,14 @@ class ScrollableStackWithIndicator extends HookWidget {
     );
 
     void handleScrolling() {
-      final hideButton = _scrolledToEnd(scrollController.position) ?? false;
-      showScrollIndicatorButton.value = !hideButton;
-      final relativeScrollPosition =
-        _getRelativeScrollPosition(contentKey, scrollController.position);
-      if (relativeScrollPosition != null) {
-        scrollIndicatorButtonOpacity.value = 1 - relativeScrollPosition;
+      if (scrollController.hasClients) {
+        final hideButton = _scrolledToEnd(scrollController.position) ?? false;
+        showScrollIndicatorButton.value = !hideButton;
+        final relativeScrollPosition =
+          _getRelativeScrollPosition(scrollController.position);
+        if (relativeScrollPosition != null) {
+          scrollIndicatorButtonOpacity.value = 1 - relativeScrollPosition;
+        }
       }
     }
 
@@ -76,11 +76,19 @@ class ScrollableStackWithIndicator extends HookWidget {
     }, [scrollController]);
 
     WidgetsBinding.instance.addPostFrameCallback((_) {
-      final contentScrollable =
-        _contentScrollable(contentKey, scrollController.position) ?? false;
-      final scrolledToEnd =
-        _scrolledToEnd(scrollController.position) ?? false;
-      showScrollIndicatorButton.value = contentScrollable && !scrolledToEnd;
+      try {
+        final contentScrollable =
+          _contentScrollable(contentKey, scrollController.position);
+        if (contentScrollable == null) {
+          failedIndicatorInitializationAttempts.value += 1;
+          return;
+        }
+        final scrolledToEnd =
+          _scrolledToEnd(scrollController.position) ?? false;
+        showScrollIndicatorButton.value = contentScrollable && !scrolledToEnd;
+      } catch (exception) {
+        failedIndicatorInitializationAttempts.value += 1;
+      }
     });
 
     return Stack(
@@ -130,12 +138,14 @@ class ScrollableStackWithIndicator extends HookWidget {
                 color: iconColor ?? PharMeTheme.iconColor,
               ),
               onPressed: () async {
-                await scrollController.animateTo(
-                  scrollController.position.maxScrollExtent,
-                  duration: Duration(milliseconds: 500),
-                  curve: Curves.linearToEaseOut,
-                );
-                showScrollIndicatorButton.value = false;
+                if (scrollController.hasClients) {
+                  await scrollController.animateTo(
+                    scrollController.position.maxScrollExtent,
+                    duration: Duration(milliseconds: 500),
+                    curve: Curves.linearToEaseOut,
+                  );
+                  showScrollIndicatorButton.value = false;
+                }
               },
             ),
           ),