Should we allow focusing on random "empty" cells?

[luongvo]

Following #8, I agree it's a feature that allows the user to edit the wrong input ✅

Screen_recording_20240828_234852.mp4

However, I don't think we should allow this behavior on "empty" cells. Saying the input is empty, the user can skip a char, such as 1_23. This is a weird behavior so I at least want to have a flag to disable this case ❌

Screen_recording_20240828_234813.mp4