I use api v3 (REST api) to get users ids and then try to fetch some of user's data from api v4 (GraphQL). in v4 I repeatedly encounter this kind of error: Could not resolve to a User with the login of 'stouset-pentest427403517596'. That was just an example. There are several user ids that generate this error: "stouset-pentest413512334053, stouset-pentest15684193814" etc. This yields to API rate limit error after some time. Is there any way to filter resulst from REST api, so before querying for user's data we know that user does not exist or so?
I've gone through both the REST API v3 and GraphQL API v4 and both of them show no possible way of checking if a user exists on GitHub. Even though this is not possible right now, I think this would make a good feedback request to GitHub themselves—it might just be implemented in the future!
Hope this helps you out!