Top node getting split when pressing enter in empty paragraph

I am working on a schema where the doc contains cards which contain blocks. But when I press enter on an empty paragraph line inside a card, PM creates an extra card and moves everything that is below the cursor on it.

https://cards-in-pm.glitch.me

https://glitch.com/edit/#!/cards-in-pm

Is that an expected behaviour? Are there options in the schema that can prevent it ? Or shall I write some code that joins cards automatically when they have been created with no apparent reason ?

The default command bound to enter will lift the current textblock out of its parent node when enter is pressed in an empty textblock. Maybe the isolating flag is useful for you here?

Thanks a lot, Marijn, you are a life saver. That does the trick. Like always, it is good to read the doc, it is better to understand the doc.