This issue has shown that, when we introduce new providers and propagate the configs to users, then remove the config ("asf" was removed and renamed to "default"), user configuration breaks
- #6358

One way of dealing with this is checking at startup time whether the configured providers are available, and if not, log a warning and fall back to the default provider.
try:
            if service not in PROXY_LISTENERS:
                LOG.debug("cannot find backend port for service %s", service)
                return
            port = PROXY_LISTENERS[service][1]
            LOG.debug("checking service health %s:%d", service, port)
            wait_for_port_status(port, expect_success=not expect_shutdown)
        except Exception:
            if print_error:
                LOG.exception("service health check %s:%d failed", service, port)
    return _check