[BUG] Resilience on undefined markdown

• I have searched for similar issues in both open and closed tickets and cannot find a duplicate.
• I have read the documentation and cannot find an answer.

Describe the bug
If the markdown parameter on the MDXEditor tag managed to be type undefined, MDX fails un-gracefully.

Typical Stack on failure

Uncaught TypeError: Cannot read properties of undefined (reading 'trim')
    at eval (/node_modules/@mdxeditor/editor/dist/plugins/core/index.js:630:81)
    at $beginUpdate (/node_modules/lexical/Lexical.dev.mjs:7386:5)
    at updateEditor (/node_modules/lexical/Lexical.dev.mjs:7465:5)
    at LexicalEditor.update (/node_modules/lexical/Lexical.dev.mjs:8830:5)
    at Object.postInit (/node_modules/@mdxeditor/editor/dist/plugins/core/index.js:628:15)
    at Object.postInit (/node_modules/@mdxeditor/editor/dist/RealmWithPlugins.js:33:62)
    at eval (/node_modules/@mdxeditor/editor/dist/RealmWithPlugins.js:50:55)
    at tap (/node_modules/@mdxeditor/editor/dist/utils/fp.js:92:3)
    at eval (/node_modules/@mdxeditor/editor/dist/RealmWithPlugins.js:44:39)
    at mountMemo (/node_modules/react-dom/cjs/react-dom.development.js:17225:19)
    at Object.useMemo (/node_modules/react-dom/cjs/react-dom.development.js:17670:16)

Suggest this is a low priority error, as your typing on inputs is clear. Work around is really on the caller to avoid the undefined state. It was just a curious runtime situation in my app, a content loading delay where I had the document meta data but had not yet retrieved the markdown, that brought this to my attention.

Reproduction

1. Start from https://codesandbox.io/p/devbox/mdx-editor-base-forked-8qg66p
2. Uncomment the body = undefined; on row 16
3. Reload the page
4. See Error in Javascript console.

Expected behavior
Editor renders empty, equivalent of a markdown parameter of and empty string ''.
No error thrown, I guess there could be a warning that the developer, has done something stupid... like I did.

Screenshots

Desktop (please complete the following information):

• MDXEditor - 3.35.1
• OS: MacOS - Sequoia 15.5 (24F74)
• Browser - Chrome Version 137.0.7151.121 (Official Build) (arm64)

Additional context
Add any other context about the problem here.

Start with the CodeSandbox reproduction and the stack-trace location in node_modules/@mdxeditor/editor/dist/plugins/core/index.js. Confirm that an undefined markdown prop no longer throws and renders an empty editor, equivalent to an empty string; the issue does not name a repository test to run.