Removing all content from the realtime wysiwyg editor prevents coeditors from editing

Steps to reproduce, as an user:

• Open a page in realtime WYSIWYG edit mode
• Open the same page in realtime WYSIWYG edit mode in an other tab.
• Write some content on the page in one of the tabs.
• Press CTRL+A to select all the content of the editor.
• Press the backspace key to erase all the content.
• Switch to the other tab and try to edit.

Expected result: On the other tab, the content is empty but it is possible to add new content to the document

Actual result: On the other tab, the editor is locked, it is impossible to write in the document.