[Logs UI] Fix the ability to switch to the ratio alert type (elastic#…

…87563)

This fixes a bug introduced with elastic#86488, which prevents the user from changing the log threshold alert type to `ratio`.

x-pack/plugins/infra/public/alerting/log_threshold/components/expression_editor/editor.tsx

@@ -14,10 +14,12 @@ import {
   ForLastExpression,
 } from '../../../../../../triggers_actions_ui/public';
 import {
-  PartialAlertParams,
   Comparator,
   isRatioAlert,
+  PartialAlertParams,
+  PartialCountAlertParams,
   PartialCriteria as PartialCriteriaType,
+  PartialRatioAlertParams,
   ThresholdType,
   timeUnitRT,
 } from '../../../../../common/alerting/logs/log_threshold/types';
@@ -47,7 +49,7 @@ interface LogsContextMeta {
 
 const DEFAULT_BASE_EXPRESSION = {
   timeSize: 5,
-  timeUnit: 'm',
+  timeUnit: 'm' as const,
 };
 
 const DEFAULT_FIELD = 'log.level';
@@ -60,7 +62,9 @@ const createDefaultCriterion = (
     ? { field: DEFAULT_FIELD, comparator: Comparator.EQ, value }
     : { field: undefined, comparator: undefined, value: undefined };
 
-const createDefaultCountAlertParams = (availableFields: LogIndexField[]) => ({
+const createDefaultCountAlertParams = (
+  availableFields: LogIndexField[]
+): PartialCountAlertParams => ({
   ...DEFAULT_BASE_EXPRESSION,
   count: {
     value: 75,
@@ -69,15 +73,17 @@ const createDefaultCountAlertParams = (availableFields: LogIndexField[]) => ({
   criteria: [createDefaultCriterion(availableFields, 'error')],
 });
 
-const createDefaultRatioAlertParams = (availableFields: LogIndexField[]) => ({
+const createDefaultRatioAlertParams = (
+  availableFields: LogIndexField[]
+): PartialRatioAlertParams => ({
   ...DEFAULT_BASE_EXPRESSION,
   count: {
     value: 2,
     comparator: Comparator.GT,
   },
   criteria: [
-    createDefaultCriterion(availableFields, 'error'),
-    createDefaultCriterion([], 'warning'),
+    [createDefaultCriterion(availableFields, 'error')],
+    [createDefaultCriterion(availableFields, 'warning')],
   ],
 });