[Bug] Undo does not join blocks back together

When you type in the middle of a sentence, press enter, continue typing and press ctrl+z to undo, it will undo the words on both blocks but won't join the blocks back together as before

Steps to reproduce:
1. Go to the demo and click somewhere in a sentence
2. Type something, press enter to goto the next line
3. Continue typing
4. Press ctrl+z to undo
5. You will notice it will remove the words from both line but the lines remain separated

Expected behavior: Undo will join back the block together to 1 block

Device, Browser, OS: Windows PC, Chrome 104

Editor.js version: 2.25.0