Only create and use the correct rich text controller for each platform

lib/features/composer/presentation/controller/rich_text_mobile_tablet_controller.dart

@@ -11,6 +11,8 @@ import 'package:tmail_ui_user/features/composer/presentation/model/inline_image.
 class RichTextMobileTabletController extends BaseRichTextController {
   HtmlEditorApi? htmlEditorApi;
 
+  final RichTextController richTextController = RichTextController();
+
   void insertImage(InlineImage inlineImage) async {
     if (inlineImage.fileInfo.isShared == true) {
       await htmlEditorApi?.moveCursorAtLastNode();
@@ -41,4 +43,11 @@ class RichTextMobileTabletController extends BaseRichTextController {
       logError('RichTextMobileTabletController::insertImageData:Exception: $e');
     }
   }
+
+  @override
+  void onClose() {
+    richTextController.dispose();
+    htmlEditorApi = null;
+    super.onClose();
+  }
 }