How can i store runtime error and show it in parent object whenever i open the parent record until that error get resolved (future apex trigger integration code).

@Saurabh Kashyap, I suppose you could ease the overall architecture to only query once, and to get quantity (not available will be understandable when quantity = 0). Indeed you have to queue the calls (queuable apex). You should handle the error code in each call as you normally do testing the getStatusCode from the http send request's response.

PS : A detail, I suppose you could be able to trigger on product required (instead of product consumed) but that does not change the logic of the integration :)

Eric