Do not crash when remove SelectableText during handle drag (#108369)

packages/flutter/lib/src/widgets/text_selection.dart

@@ -444,6 +444,9 @@ class TextSelectionOverlay {
   late Offset _dragEndPosition;
 
   void _handleSelectionEndHandleDragStart(DragStartDetails details) {
+    if (!renderObject.attached) {
+      return;
+    }
     final Size handleSize = selectionControls!.getHandleSize(
       renderObject.preferredLineHeight,
     );
@@ -451,6 +454,9 @@ class TextSelectionOverlay {
   }
 
   void _handleSelectionEndHandleDragUpdate(DragUpdateDetails details) {
+    if (!renderObject.attached) {
+      return;
+    }
     _dragEndPosition += details.delta;
     final TextPosition position = renderObject.getPositionForPoint(_dragEndPosition);
 
@@ -492,6 +498,9 @@ class TextSelectionOverlay {
   late Offset _dragStartPosition;
 
   void _handleSelectionStartHandleDragStart(DragStartDetails details) {
+    if (!renderObject.attached) {
+      return;
+    }
     final Size handleSize = selectionControls!.getHandleSize(
       renderObject.preferredLineHeight,
     );
@@ -499,6 +508,9 @@ class TextSelectionOverlay {
   }
 
   void _handleSelectionStartHandleDragUpdate(DragUpdateDetails details) {
+    if (!renderObject.attached) {
+      return;
+    }
     _dragStartPosition += details.delta;
     final TextPosition position = renderObject.getPositionForPoint(_dragStartPosition);
 

packages/flutter/test/widgets/selectable_text_test.dart

@@ -176,6 +176,74 @@ void main() {
     );
   }
 
+  testWidgets('Do not crash when remove SelectableText during handle drag', (WidgetTester tester) async {
+    // Regression test https://github.com/flutter/flutter/issues/108242
+    bool isShow = true;
+    late StateSetter setter;
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: StatefulBuilder(
+            builder: (BuildContext context, StateSetter setState) {
+              setter = setState;
+              if (isShow) {
+                return const SelectableText(
+                  'abc def ghi',
+                  dragStartBehavior: DragStartBehavior.down,
+                );
+              } else {
+                return const SizedBox.shrink();
+              }
+            },
+          ),
+        ),
+      ),
+    );
+
+    final EditableText editableTextWidget = tester.widget(find.byType(EditableText));
+    final TextEditingController controller = editableTextWidget.controller;
+
+    // Long press the 'e' to select 'def'.
+    final Offset ePos = textOffsetToPosition(tester, 5);
+    TestGesture gesture = await tester.startGesture(ePos, pointer: 7);
+    await tester.pump(const Duration(seconds: 2));
+    await gesture.up();
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 200)); // skip past the frame where the opacity is zero
+
+    final TextSelection selection = controller.selection;
+    expect(selection.baseOffset, 4);
+    expect(selection.extentOffset, 7);
+
+    final RenderEditable renderEditable = findRenderEditable(tester);
+    final List<TextSelectionPoint> endpoints = globalize(
+      renderEditable.getEndpointsForSelection(selection),
+      renderEditable,
+    );
+    expect(endpoints.length, 2);
+
+    // Drag the left handle to the left.
+    final Offset handlePos = endpoints[0].point + const Offset(-1.0, 1.0);
+    final Offset newHandlePos = textOffsetToPosition(tester, 1);
+    final Offset newHandlePos1 = textOffsetToPosition(tester, 0);
+    gesture = await tester.startGesture(handlePos, pointer: 7);
+    await tester.pump();
+    await gesture.moveTo(newHandlePos);
+    await tester.pump();
+
+    // Unmount the SelectableText during handle drag
+    setter(() {
+      isShow = false;
+    });
+    await tester.pump();
+
+    await gesture.moveTo(newHandlePos1);
+    await tester.pump(); // Do not crash here
+
+    await gesture.up();
+    await tester.pump();
+  });
+
   testWidgets('has expected defaults', (WidgetTester tester) async {
     await tester.pumpWidget(
       boilerplate(