To copy data from column A to column C

If Cell A empty, to take data from column B

If both cell empty mention Nil

Google Sheetlink - <https://docs.google.com/spreadsheets/d/19M0DlaRY_JgcgyyG2GpGhuEpdqMiDX-y2YoTA0TIakQ/edit?usp=sharing>

[![enter image description here](https://i.stack.imgur.com/IeB7S.png)](https://i.stack.imgur.com/IeB7S.png)

I have tried

```
=ARRAYFORMULA(IF(A2="",A2,B2))

```

The results are incorrect