Nested <code> elements

Steps to reproduce:

1. Type "A B C D E X a b c d e" in a paragraph.
2. Select "X" and click on InlineCode button (with "<>" icon)
3. Select "E X a" and click on InlineCode button
4. Select "D E X a b" and click on InlineCode button

And so on...

Expected behavior:

One `` element instead of nested `` elements

Editor.js version: 2.30.7


Reproduce the nested inline-code behavior in Editor.js 2.30.7 using the listed selection steps in Firefox or Chrome, then inspect the InlineCode tool entry point. Done means repeated overlapping selections produce one element rather than nested elements.

索引モデルが issue の本文から書いたものです。