Cannot read properties of null (reading 'editing') for open MathType in Online Builder with React

Question

Provide detailed reproduction steps (if any)

1- create a custom build with online builder 2- download and add to root project and install npm with command npm i file:./plugins/ckeditor5 3- npm i ckeditor5/react 4- my codes in a component:

import {CKEditor} from "@ckeditor/ckeditor5-react";
import Editor from "ckeditor5-custom-build/build/ckeditor"

<CKEditor
                            editor={Editor}
                            config={editorConfig}
                            onChange={questionHandler}
                            onReady={questionEditorClass}
                        />

Other details

• Browser: chrome and firefox
• OS: MacOs
• First affected CKEditor version: ckeditor5/react 6.1.0
• Installed CKEditor plugins: MathType

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when open MathType or ChemType without problem but open for first time have error in chrome:

when open MathType or ChemType without problem but open for first time have error in firefox: