Is your feature request related to a problem? Please describe.

Currently if one removed something from nucleus position it sets value to the empty string. Doesn't look convenient.

Describe the solution you'd like

Placeholder is appeared.

Difficulty: How difficult would it be? (Trivial, Very Easy, Easy, Moderate, Hard, Very Hard, Tedious, Backbreaking)

Probably, Moderate

Additional context

Current behavior leads to this: