1. Open to update or add Summary to a Flow board topic - click on Mention or Link.
2. When Link/Mention inspector open, click on 'Save summary' - it hangs (only refreshing page will work) and

"Uncaught TypeError: Cannot read property 'ownerDocument' of undefined" is displayed.

Note:

• The same steps do not produce the error when are done in posts or Board description
• Article pages will not display the error either.