Inconsistent HTTP status codes for removing nonexistent labels from 'E' events
If you try to remove a label that does not exist from an 'E' event, you get a 400 error. If you try to perform this operation on other kinds of events, you get a 404 error, which I think is the correct behavior.
See https://sentry.io/organizations/ligo-caltech/issues/1018090875.