Steps to reproduce:
1. Log in on admin user
2. Start dashboard edition (click 'Customize your dashboard')
3. In dashboard builder edit 'Ibexa news' block (also occurs on Recent activity block)
4. Click 'Save and close' with no changes in block

Note! = occurs also on page builder blocks

Actual result:
'Uncaught TypeError' occurs after block edition

Expected result:
No error appears