Null values ​​in Mass Actions

I want to increase the price by 40% on the price column. To do this, I used the tutorial in this link:
https://www.hikashop.com/forum/mass-actions/861153-change-price-of-all-products-by-percentage.htmlhttps://www.hikashop.com/forum/mass-actions/861153-change-price-of-all-products-by-percentage.html

This method works well on products that do not have variants, but if you have a product that has variants, it sets the price of the variant product to zero. That is, it writes the number 0 in the price column. Therefore, variant products cannot inherit the price from the main product.
As far as I know, in the backend product management of Hikashop, we cannot give a product a zero price, but an empty price column means that it is zero. (Although it would be nice if we could have a zero value and a null value for variant products so that those that are zero are free and those that are null inherit the price from the main product).
Therefore, the correct value 0 should not be written there. I think this is implemented incorrectly.
How can I change the price of variant products that are not null and also the price of the main products by 40%, but leave the variant products whose price is null unchanged and the zero value in their price column not calculated?