"Uncaught TypeError: Cannot read property 'remove' of null" error occurs from Selection field.

Steps:

1. Go to Admin panel / Content Types / Content.
2. Create new Content type.
3. Add Text line field.
4. Add Selection field.
5. Add two options.
6. Save.
7. Go to Content / Content structure.
8. Create a new content item using new CT.
9. Fill name.
10. Choose the empty value from the selection dropdown list.
11. Check browser console.

Actual: Uncaught TypeError: Cannot read property 'remove' of null.

Remarks: Occurs on Platform and EE (demo rc3 also).