Describe the bug
In Gutenberg 6.5.
Shows this error in the console :
react-dom.min.b694e242.js:103 TypeError: Cannot read property 'trim' of undefined

To reproduce

1. Copy text from a source where there is a tag with no href
   or
   create a link with no href when editing a block in HTML mode
2. In visual mode, click on the link or drag over it (like when you want to select text containing a anchor with no href).
3. Oups, block is gone!

Expected behavior
The pop-up to enter the adress should show up empty

Desktop:

• OS: Windows 10
• Browser: Chrome
• Version: 77

Thank you!