[Memory leak] Handle dispose in MobileEditorWidget

core/lib/utils/html/html_utils.dart

@@ -48,8 +48,11 @@ class HtmlUtils {
       editor.parentNode.replaceChild(newEditor, editor);''',
     name: 'unregisterDropListener');
 
-  static registerSelectionChangeListener(String viewId) => (
-    script: '''
+  static ({String name, String script}) registerSelectionChangeListener(
+    String viewId,
+  ) =>
+      (
+        script: '''
       let lastSelectedText = '';
 
       const sendSelectionChangeMessage = (data) => {
@@ -149,7 +152,8 @@ class HtmlUtils {
         }
       });
     ''',
-    name: 'onSelectionChange');
+        name: 'onSelectionChange',
+      );
 
   static const collapseSelectionToEnd = (
     script: '''

lib/features/composer/presentation/widgets/mobile/mobile_editor_widget.dart

@@ -38,6 +38,8 @@ class MobileEditorWidget extends StatefulWidget {
 class _MobileEditorState extends State<MobileEditorWidget> with TextSelectionMixin {
 
   late String _createdViewId;
+  InAppWebViewController? _editorController;
+  ({String name, String script})? registerSelectionChange;
 
   @override
   void initState() {
@@ -45,17 +47,29 @@ class _MobileEditorState extends State<MobileEditorWidget> with TextSelectionMix
     _createdViewId = HtmlUtils.getRandString(10);
   }
 
+  @override
+  void dispose() {
+    if (registerSelectionChange != null) {
+      _editorController?.removeJavaScriptHandler(
+        handlerName: registerSelectionChange!.name,
+      );
+    }
+    _editorController?.dispose();
+    _editorController = null;
+    super.dispose();
+  }
+
   @override
   void Function(TextSelectionData?)? get onSelectionChanged => widget.onTextSelectionChanged;
 
   Future<void> _setupSelectionListener(HtmlEditorApi editorApi) async {
-    final webViewController = editorApi.webViewController;
+    _editorController = editorApi.webViewController;
 
-    final registerSelectionChange =
+    registerSelectionChange =
         HtmlUtils.registerSelectionChangeListener(_createdViewId);
 
-    webViewController.addJavaScriptHandler(
-      handlerName: registerSelectionChange.name,
+    _editorController?.addJavaScriptHandler(
+      handlerName: registerSelectionChange!.name,
       callback: (args) {
         if (!mounted) return;
 
@@ -68,8 +82,8 @@ class _MobileEditorState extends State<MobileEditorWidget> with TextSelectionMix
       },
     );
 
-    await webViewController.evaluateJavascript(
-      source: registerSelectionChange.script,
+    await _editorController?.evaluateJavascript(
+      source: registerSelectionChange!.script,
     );
   }