Use native lang features instead isEmpty

[MAILPOET-3763]

assets/js/src/newsletters/types/re_engagement/re_engagement.tsx

@@ -3,7 +3,6 @@ import {
   __,
   assoc,
   compose,
-  isEmpty,
 } from 'lodash/fp';
 import { useHistory } from 'react-router-dom';
 
@@ -18,7 +17,7 @@ import ListingHeadingStepsRoute from '../../listings/heading_steps_route';
 
 export function NewsletterTypeReEngagement(): JSX.Element {
   let defaultAfterTime = '';
-  if (!isEmpty(MailPoet.settings.deactivate_subscriber_after_inactive_days)) {
+  if (MailPoet.settings.deactivate_subscriber_after_inactive_days) {
     defaultAfterTime = (
       (
         Math.floor(
@@ -87,7 +86,7 @@ export function NewsletterTypeReEngagement(): JSX.Element {
           isFullWidth
           onClick={handleNext}
           type="button"
-          isDisabled={isEmpty(options.afterTimeNumber) || loading}
+          isDisabled={(!options.afterTimeNumber) || loading}
           withSpinner={loading}
         >
           {MailPoet.I18n.t('next')}

assets/js/src/newsletters/types/re_engagement/scheduling.tsx

@@ -1,6 +1,5 @@
 import React from 'react';
 import ReactStringReplace from 'react-string-replace';
-import { isEmpty } from 'lodash/fp';
 
 import MailPoet from 'mailpoet';
 import Heading from 'common/typography/heading/heading';
@@ -26,6 +25,7 @@ export function Scheduling({
 }: Props): JSX.Element {
   const daysInPeriod = afterTimeType === 'weeks' ? 7 : 30;
   const daysSelected = Number(afterTimeNumber) * daysInPeriod;
+
   return (
     <>
       <Heading level={4}>{MailPoet.I18n.t('selectEventToSendReEngagementEmail')}</Heading>
@@ -48,7 +48,7 @@ export function Scheduling({
         </Select>
       </Grid.CenteredRow>
       {
-        ((!isEmpty(inactiveSubscribersPeriod)) && (inactiveSubscribersPeriod <= daysSelected)) && (
+        ((!!inactiveSubscribersPeriod) && (inactiveSubscribersPeriod <= daysSelected)) && (
           <p className="mailpoet-re-engagement-scheduling-note">
             {
               ReactStringReplace(