JSON Bone breakes if the JSON-Object is invalid

[cheeaza]

The JSONBone does not validate its input in the admin interface, allowing
invalid JSON to be saved. Once invalid JSON is persisted, the admin is no
longer able to load the skel list — it appears to get stuck in an infinite
reload loop.

Steps to Reproduce

1. Open any skeleton with a JSONBone field in the admin
2. Enter an invalid JSON value (e.g. "test") and save
3. Navigate to the skel list view
4. Observe the admin reloading continuously without rendering the list

Admin Version: 4.14.6
Core Version: 3.8.26