Don't persist empty form data when leaving a form step

If the active step form is invalid we will receive no data, so we must
not persist that lest the form blows up on absent values when we later
navigate back.

x-pack/plugins/security_solution/public/detections/pages/detection_engine/rules/edit/index.tsx

@@ -16,6 +16,7 @@ import {
 import { FormattedMessage } from '@kbn/i18n/react';
 import React, { FC, memo, useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import { useParams, useHistory } from 'react-router-dom';
+import isEmpty from 'lodash/isEmpty';
 
 import { useRule, usePersistRule } from '../../../../containers/detection_engine/rules';
 import { useListsConfig } from '../../../../containers/detection_engine/lists/use_lists_config';
@@ -263,7 +264,7 @@ const EditRulePageComponent: FC = () => {
     async (tab: EuiTabbedContentTab) => {
       const activeStepData = await stepsForm.current[activeStep]?.submit();
 
-      if (activeStepData != null) {
+      if (activeStepData != null && !isEmpty(activeStepData.data)) {
         setStepData(activeStep, activeStepData.data, activeStepData.isValid);
       }
       setInitForm(true);