Beta editor: Auto-indent doesn't work in code blocks with an unknown language type (including mermaid)

[personalizedrefrigerator]

Operating system

Android

Joplin version

2.14.5

Desktop version info

No response

Current behaviour

1. Create a note with the following content:

Test:
```mermaid
flowchart LR
    A --> B
```

2. Move the cursor to the end of the A --> B line and press enter
3. Observe that the indentation from the previous line is not continued.

Expected behaviour

Indentation from the previous line should be continued.

Logs

No response