FetchAdditionalProducts - Unity 5.4

Any chance for a code example of how this function should be used?
When I fetch additional items sometimes some of them return without price and the previous items without price cannot be found by id even though they’re shown in the products array of the StoreController…

Here is how I tried to solve this problem.

Everything should be OK, but somehow products are unavailable after I use FetchAdditionalProducts.
Maybe this will be a start for you.