Describe the bug
When trying to remove a link, emptying the placeholder/value of the URL in the link should work.

To reproduce
Steps to reproduce the behavior:

1. Edit an existing link, aiming to remove the link
2. Empty the value of the URL in the link, and try to "submit" this change

Expected behavior
The editor will prompt the user to add a "Please fill in this field". I would expect that submitting an empty value on a link would remove the link.

Screenshots

Editor version (please complete the following information):

• WordPress 5.5.1
• The described behaviour happens both with and without the plugin installed (v 9.0.0)

Desktop (please complete the following information):

• OS: MacOs High Sierra 10.13.6
• Google Chrome 85.0.4183.102

Additional context
I have found several people struggling to remove a link, expecting that removing the URL would just remove the link.