Cannot edit a content item with image asset and user fields.

Steps:

1. Create a CT with fields: ezstring, ezimageasset, ezuser (none required).
2. Create new item using this CT, fill only ezstring and ezuser.
3. Publish.
4. Edit the item.
5. Fill ezimageasset field, use Upload image button.
6. Publish.
7. Try to edit again.

Actual: Editor doesn't load, error occurs in browser console (screen1):

Uncaught TypeError: Cannot read property 'classList' of null

Remarks: When switching to this content item in admin in view mode another error occurs (screen2):

Uncaught TypeError: Cannot read property 'addEventListener' of null