Enter Key Breaks Children in Custom Toggleable Blocks

[FatefulNur]

Describe the bug When pressing Enter inside a custom toggleable block, the children are broken unexpectedly.

• If the cursor is on the toggle title, all children should be preserved, but they are not.
• If the cursor is inside the children, pressing Enter should move the cursor to the next child (if it exists) or create a new default block.

To Reproduce

1. Open the example: https://www.blocknotejs.org/examples/custom-schema/toggleable-blocks
2. Place the cursor in the toggle title and press Enter.
3. Observe that the children are broken.

Misc

• Node version: 22.13.0
• Package manager: npm
• Browser: Firefox
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https://github.com/user-attachments/assets/eb85ca78-7b74-497d-944e-27017ba6f675