Steps to reproduce:

1. Log in to back office.
2. Go to Content / Content Types / Content.
3. Start creating new content.
4. Scroll page down to Field type section and click on 'Search' button in search input.
5. Add random field to Field definition section and then click on 'Search' button in search input (Field section).

Actual result:

See attached screenshot and watch gif: https://recordit.co/YD3kKGaHrL

• Missing translation for notification.
• An error 500 occurred 

Call to a member function getName() on null 

Expected result:

• Properly displayed translation.
• No exception occurs.