[Metrics UI] Fix evaluating rate-aggregated alerts when there's no normalized value

[Zacqary]

Summary

Fixes a bug we uncovered when trying to preview a metric threshold alert with a Rate aggregator. The Rate agg is normally supposed to return buckets that look like this:

"aggregatedValue_max": {
  "value": 4.59
},
"aggregatedValue_deriv": {
  "value": 0.3199999999999994,
  "normalized_value": 0.0005333333333333323
},
"aggregatedValue": {
  "value": 0.0005333333333333323
}

However, since the executor is expecting aggregatedValue to exist, it errors out when encountering something like:

"aggregatedValue_max": {
  "value": null
}

or

"aggregatedValue_max": {
  "value": 5.72
},
"aggregatedValue_deriv": {
  "value": null,
  "normalized_value": null
}

This PR adds a handler for these cases. Rate-aggregated alerts will now evaluate as No Data in these cases (and will preview correctly)

Checklist

• Unit or functional tests were updated or added to match the most common scenarios

[elasticmachine]

Pinging @elastic/logs-metrics-ui (Team:logs-metrics-ui)

[simianhacker]

LGTM... Confirmed the alerts are triggering and the preview works as expected.

[Zacqary]

@elasticmachine merge upstream

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 30cc862

Build metrics

✅ unchanged

History

• 💔 Build #64914 failed 29ee75f

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream