Show error message on failed namespace change
Problem
When a namespace change is not allowed we just redirect back to the subscription's page. It would be nice to show an error message to let the user know what's going on. With https://gitlab.com/gitlab-org/customers-gitlab-com/-/merge_requests/1635 there will be a general error message in case of an error that could be shown.
Proposal
Process error in frontend to inform the user about an error.
Result
User knows about the error.