Infinite loop on ENTER/LEAVE when numbered list gets too long

[nixxquality]

Describe the bug When a numbered list reaches around 320 elements if you try to add a new line you will be disconnected from the pad and put in an ENTER/LEAVE loop. When you refresh your change will be undone.

To Reproduce Steps to reproduce the behavior:

1. Create a new pad
2. Start a numbered list
3. Just write a and press enter 320 times
4. When you get to 321 or 322 you will be kicked out

Expected behavior Numbered lists should be as long as they need to be

Server:

• Etherpad version: v1.8.18 (I just updated to see if it would fix it)
• OS: CentOS Stream release 8
• Node.js version (node --version): v13.13.0
• npm version (npm --version): 6.14.4
• Is the server free of plugins: Tried with and without plugins, no change

Desktop:

• OS: Windows
• Browser: Vivaldi
• Version: 5.2.2623.46 (Stable channel) (64-bit)

[DooMMasteR]

might be related to #5454 i guess.