message: Monitoring: Fix handling of ServiceMonitor's matchExpressions
  For the monitoring targets UI pages, we also need to handle the case
  where a ServiceMonitor has `matchExpressions`, but no `matchLabels`.
diff: @@ -52,7 +52,7 @@ const ServiceMonitor: React.FC<{ target: Target }> = ({ target }) => {
  monitors,
  ({ spec }) =>
  service &&
  - (spec.selector.matchLabels === undefined ||
  + ((spec.selector.matchLabels === undefined && spec.selector.matchExpressions === undefined) ||
  new LabelSelector(spec.selector).matchesLabels(service.metadata.labels ?? {})) &&
  (spec.namespaceSelector?.matchNames === undefined ||
  _.includes(spec.namespaceSelector?.matchNames, service.metadata.namespace)),
  