Cherry-pick "[SuperTextField][mobile] Fix exception when updateTextAndSelection (Resolves #1229) (#1234)" to stable

super_editor/lib/src/infrastructure/super_textfield/infrastructure/text_scrollview.dart

@@ -968,6 +968,11 @@ class TextScrollController with ChangeNotifier {
       return;
     }
 
+    if (_textController.text.text.isEmpty) {
+      // There is no text to make visible.
+      return;
+    }
+
     final baseCharacterRect = _delegate!.getCharacterRectAtPosition(_textController.selection.base);
     _ensureRectIsVisible(baseCharacterRect);
   }
@@ -987,6 +992,11 @@ class TextScrollController with ChangeNotifier {
       return;
     }
 
+    if (_textController.text.text.isEmpty) {
+      // There is no text to make visible.
+      return;
+    }
+
     final characterIndex = _textController.selection.extentOffset >= _textController.text.text.length
         ? _textController.text.text.length - 1
         : _textController.selection.extentOffset;

super_editor/test/super_textfield/super_textfield_auto_scroll_test.dart

@@ -5,13 +5,14 @@ import 'package:super_editor/src/infrastructure/super_textfield/metrics.dart';
 import 'package:super_editor/super_editor.dart';
 
 import '../test_tools.dart';
+import 'super_textfield_robot.dart';
 
 const screenSizeWithoutKeyboard = Size(400, 800);
 const screenSizeWithKeyboard = Size(400, 300);
 
 void main() {
-  group('SuperTextField on mobile', () {
-    group('with an ancestor Scrollable', () {
+  group('SuperTextField', () {
+    group('on mobile with an ancestor Scrollable', () {
       _testWidgetsOnMobileWithKeyboard('auto scrolls when focused in single-line', (tester, keyboardToggle) async {
         await _pumpTestApp(
           tester,
@@ -116,6 +117,37 @@ void main() {
         expect(finalTopLeft, initialTopLeft);
       });
     });
+
+    testWidgetsOnAllPlatforms('auto scroll doesn\'t crash when text is empty', (tester) async {
+      final controller = AttributedTextEditingController(
+        text: AttributedText(text: 'Text before'),
+      );
+
+      await _pumpScaffold(
+        tester,
+        SuperTextField(
+          textController: controller,
+        ),
+      );
+
+      // Place caret at the end of the text field.
+      await tester.placeCaretInSuperTextField(11);
+
+      // Clear the text and changes the selection to the beginning of the text.
+      controller.updateTextAndSelection(
+        text: AttributedText(),
+        selection: const TextSelection.collapsed(offset: 0),
+      );
+      await tester.pump();
+
+      /// When text or selection changes, we auto scroll to ensure that the selecion is visible.
+      /// To do so, we need to get the bounds of the character at the selection extent.
+      ///
+      /// If we attempt to auto scroll when the text is empty, a crash happens because there isn't a
+      /// character at the selection extent.
+      ///
+      /// Reaching this point means we didn't attempt to auto scroll after clearing the text.
+    });
   });
 }
 
@@ -149,6 +181,22 @@ Future<void> _pumpTestApp(
   await tester.pump();
 }
 
+/// Pumps a scaffold with a centered [child].
+Future<void> _pumpScaffold(WidgetTester tester, Widget child) async {
+  await tester.pumpWidget(
+    MaterialApp(
+      home: Scaffold(
+        body: Center(
+          child: SizedBox(
+            width: 300,
+            child: child,
+          ),
+        ),
+      ),
+    ),
+  );
+}
+
 @isTestGroup
 void _testWidgetsOnMobileWithKeyboard(
   String description,

super_editor/test/super_textfield/type_into_super_textfield_test.dart

@@ -2,8 +2,10 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_test_robots/flutter_test_robots.dart';
+import 'package:super_editor/src/test/super_editor_test/supereditor_robot.dart';
 import 'package:super_editor/super_editor.dart';
 
+import '../test_tools.dart';
 import 'super_textfield_inspector.dart';
 import 'super_textfield_robot.dart';