[Bug] `Cannot read property 'updateCurrentInput' of undefined` when adding two instances of the editor

Describe a bug.
when I try to add 2 instances, the editor throws an error:
```
editorjs@latest:6 Uncaught TypeError: Cannot read property 'updateCurrentInput' of undefined
at y.value (editorjs@latest:6)
at k.value (editorjs@latest:6)
at HTMLDocument. (editorjs@latest:6)
```

Steps to reproduce:
1. add the EditorJS script
2. Add 2 divs with different ID (ex: `editor1` and `editor2`)
3. Initialize those divs with the editor
4. try clicking the (+) icon and adding some blocks
5. Check console

Expected behavior:
No errors when creating multiple instances

Screenshots:

Device, Browser, OS:
Windows 10, Chrome Version 88.0.4324.150 (Official Build) (64-bit)

Editor.js version:
Latest

Plugins you use with their versions:
No plugins, straight from the CDN