Typing ``` then Enter throws "Language is not supported" and corrupts cursor/deletion

What’s broken?

Typing ``` (with no language name) and pressing Enter creates a code block whose language is an empty string. The highlighter then throws Uncaught Error: Language is not supported. After that, the cursor position is wrong, and Backspace/Delete no longer behave correctly in that block.

What did you expect to happen?

Typing ``` and pressing Enter should create a normal code block with the default language (e.g. text), without throwing. The cursor should land inside the block, and Backspace/Delete should work as usual.

Steps to reproduce

1. Open any BlockNote editor with @blocknote/code-block enabled (the official code-block example is enough).
2. In an empty paragraph, type ``` (three backticks, no language name).
3. Press Enter.

Result: the console throws Uncaught Error: Language is not supported. After that, the cursor is in the wrong place, and Backspace/Delete in that block are also wrong.

```js then Enter does not reproduce this.

BlockNote version

v0.54.0

Environment

No response

Additional context

No response

Contribution

• I'd be interested in contributing a fix for this issue

Sponsor

• I'm a sponsor and would appreciate if you could look into this sooner than later 💖

Start with the @blocknote/code-block entry point and reproduce the issue in the official code-block example using ``` followed by Enter. Trace how an empty language is handled, then verify that the block uses a default language, no error occurs, the cursor lands inside it, and Backspace/Delete behave normally.