Unhandled promise rejection when using Repository.isCollaborator()

[sulkaharo]

When calling Repository.isCollaborator(), the a UnhandledPromiseRejectionWarning: Error: 404 error making request get https://api.github.com/repos/org/repo/collaborators/xxx: "Not Found" is thrown when a user is not a collaborator, instead of returning false, and if the user is a collaborator, the request object is returned with blank data field. Based on the documentation, the promise should resolve to a boolean, but this doesn't seem to be the case with how actual behaviour.