Fixes a rich text property crash caused by empty markup round-tripping as null after translation.

What's fixed

• Empty RTE markup no longer breaks the node. A rich text property with empty markup (for example, a block-only rich text value with no plain text) could come back from translation stored as {"markup": null, "blocks": ...} instead of {"markup": "", "blocks": ...}. That made the content node unopenable in the backoffice, failing with ArgumentNullException: Value cannot be null. (Parameter 'input') from RichTextPropertyValueEditor.ToEditor.

If you have content already affected by this, the stored property value will need "markup": null corrected back to "markup": "".

Published to NuGet.