[8.15] [ML][Rules] Fixes deletion in Check interval input for anomaly…

… detection rule (#193420) (#193730)

# Backport

This will backport the following commits from `main` to `8.15`:
- [[ML][Rules] Fixes deletion in Check interval input for anomaly
detection rule (#193420)](#193420)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Robert
Jaszczurek","email":"[email protected]"},"sourceCommit":{"committedDate":"2024-09-23T14:27:01Z","message":"[ML][Rules]
Fixes deletion in Check interval input for anomaly detection rule
(#193420)\n\n## Summary\r\n\r\nIt was trying to parse `null`
values.\r\nAfter:\r\n\r\n![image](https://github.com/user-attachments/assets/82d24663-a895-4ad4-bc01-fb76b883bc66)\r\n\r\nFixes
[#190732](https://github.com/elastic/kibana/issues/190732)\r\n\r\n---------\r\n\r\nCo-authored-by:
kibanamachine
<[email protected]>","sha":"65b7bf9586480b522393905ff21324f473ee90ed","branchLabelMapping":{"^v9.0.0$":"main","^v8.16.0$":"8.x","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:fix",":ml","v9.0.0","Team:ML","backport:prev-major"],"title":"[ML][Rules]
Fixes deletion in Check interval input for anomaly detection
rule","number":193420,"url":"https://github.com/elastic/kibana/pull/193420","mergeCommit":{"message":"[ML][Rules]
Fixes deletion in Check interval input for anomaly detection rule
(#193420)\n\n## Summary\r\n\r\nIt was trying to parse `null`
values.\r\nAfter:\r\n\r\n![image](https://github.com/user-attachments/assets/82d24663-a895-4ad4-bc01-fb76b883bc66)\r\n\r\nFixes
[#190732](https://github.com/elastic/kibana/issues/190732)\r\n\r\n---------\r\n\r\nCo-authored-by:
kibanamachine
<[email protected]>","sha":"65b7bf9586480b522393905ff21324f473ee90ed"}},"sourceBranch":"main","suggestedTargetBranches":[],"targetPullRequestStates":[{"branch":"main","label":"v9.0.0","branchLabelMappingKey":"^v9.0.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/193420","number":193420,"mergeCommit":{"message":"[ML][Rules]
Fixes deletion in Check interval input for anomaly detection rule
(#193420)\n\n## Summary\r\n\r\nIt was trying to parse `null`
values.\r\nAfter:\r\n\r\n![image](https://github.com/user-attachments/assets/82d24663-a895-4ad4-bc01-fb76b883bc66)\r\n\r\nFixes
[#190732](https://github.com/elastic/kibana/issues/190732)\r\n\r\n---------\r\n\r\nCo-authored-by:
kibanamachine
<[email protected]>","sha":"65b7bf9586480b522393905ff21324f473ee90ed"}}]}]
BACKPORT-->

Co-authored-by: Robert Jaszczurek <[email protected]>

x-pack/plugins/ml/public/alerting/anomaly_detection_rule/config_validator.tsx

@@ -32,13 +32,15 @@ export const ConfigValidator: FC<ConfigValidatorProps> = React.memo(
   ({ jobConfigs = [], alertInterval, alertParams, alertNotifyWhen, maxNumberOfBuckets }) => {
     if (jobConfigs.length === 0) return null;
 
-    const alertIntervalInSeconds = parseInterval(alertInterval)!.asSeconds();
+    const alertIntervalInSeconds = parseInterval(alertInterval)?.asSeconds();
 
     const lookbackIntervalInSeconds =
       !!alertParams.lookbackInterval && parseInterval(alertParams.lookbackInterval)?.asSeconds();
 
     const isAlertIntervalTooHigh =
-      lookbackIntervalInSeconds && lookbackIntervalInSeconds < alertIntervalInSeconds;
+      lookbackIntervalInSeconds &&
+      alertIntervalInSeconds &&
+      lookbackIntervalInSeconds < alertIntervalInSeconds;
 
     const jobWithoutStartedDatafeed = jobConfigs
       .filter((job) => job.datafeed_config.state !== DATAFEED_STATE.STARTED)
@@ -49,6 +51,7 @@ export const ConfigValidator: FC<ConfigValidatorProps> = React.memo(
     const notifyWhenWarning =
       alertNotifyWhen === 'onActiveAlert' &&
       lookbackIntervalInSeconds &&
+      alertIntervalInSeconds &&
       alertIntervalInSeconds < lookbackIntervalInSeconds;
 
     const bucketSpanDuration = parseInterval(jobConfigs[0].analysis_config.bucket_span!);